Try the shortbow
The Bard has the following weapon proficiencies
Weapons: Simple weapons, hand crossbows, longswords, rapiers, shortswords
As a College of Creation bard, you do not gain better proficiencies, so those are the ones to work with. You are not considering range, but in many cases it is an important aspect -- if both you and the opponent have ranged weapons, you can shoot them with impunity without being hit back if you have better range.
Sling. The lightest and smallest weapon you could use would be a sling, weighs next to nothing, takes next to no space, but deals only 1d4 damage at 30/120 range. I would not consider that "decent" damage, as it is the low end of the ranged weapon damage range. You could also use darts but they are both heavier and have even shorter range, so worse (they mostly make sense if your character is Strength-based, because as a thrown weapon, you can use your Strength on the ranged attack with them).
Shortbow. I think the best compromise between light, not too bulky and damage is the shortbow. It only weighs 2 pounds, has a solid range with 80/320, and deals middling damge with 1d6. (If you were a College of Valor bard, this would be the clear best option once you can get Extra Attack, as it gives you a second attack with good range and decent damage, better than a single attack with a crossbow.)
Hand Crossbow. If you are really into "not bulky", you could also try the one-handed hand crossbow. It is however heavier than the shortbow at 3 pounds, you still need both hands to reload it, and it has lower range at only 30/120 and like all crossbows, it has the added disadvantage of the Loading trait, meaning you can at most attack one time with it each round. But in the beginning -- and overall as a College of Creation bard -- you have only 1 attack anyways, and therefore that is a non-issue.
Light Crossbow. This deals the most damage (1d8 vs the shortbows 1d6), but is both bulky and heavier at 5 pounds, and if the "not heavy" is important to you, better expected damage by 1 point, may not be worth it. Among your options, it is the worst fit for not heavy and not bulky, in exachange for most damage.
From a purely mechanical perspective, for a tier 1 bard the light crossbow is the best choice, as it has the overall highest range and damage output, and the downside of higher weight can be managed.
You may run into minor issues if you play the bard Dexterity-based and "dump" Strength1 by putting your lowest value on it -- typcially 8 unless you roll for your ability scores, and you also use the variant encumberance rules. In that case, any weight over 40 pounds will start to slow you down, which is a significant downside.
A typical adventuring kit like the Explorer's Pack already weighs 48 pounds - so it can be hard to cut stuff and make room for studded leather armor weighing 13 pounds and additional weapon weight. In that case, every pound counts. But even then you can make it work by carrying fewer rations, lighter or no rope, using a lantern instead of torches, etc.
In summary: on tier one, a simple light crossbow will have more impact on combat than Vicious Mockery in most situations, so it is a reasonable policy to either only take the cantrip on level 4, or maybe not at all and take another cantrip instead. I think this take may be somewhat controversial, so let me elaborate this with some number-crunching.
Vicious Mockery obviously is subpar if seen as a pure damage cantrip, expecially on tier one; a light crossbow or even a shortbow will deal more damage on tier one. Vicious Mockery is save or nothing on a Wisdom save that cannot crit and has about a 60% fail rate, so you can expect 1d4 times 60%, or on average 1.5 points of damage. Light crossbow, against a typical AC opponent has a 65% hit rate, so you can expect 1d8 + 3 (with 14 Dexterity) times 65%, plus critical damage worth 4.5 points times 5% from a natural 20, or on average more than 5 points of expected damage per attack, 6 points if you prioritze Dexterity over Charisma and put your best value on it using point buy and a ability score increase). That is a lot better, more than three or four times as much.
The value of Vicious Mockery however is not entirely in the damage, it also is imposing Disadvantage on the opponent's next attack. How much is that worth?
In higher tiers, the value of this goes down as many more monsters tend to have multiattack, but in tier one, this can successfuly blank the entire attack of a strong opponent like an ogre. The to hit chance of a monster obviously depends on the character AC and the monster's to hit. On tier 1, character ACs range from about 15 to 18 (e.g. Rogue with Dex 16 and studded leather, wizard with Dex 14 and mage armor to fighter with chainmail and shield), so let's assume an average of AC 16. Sticking with the ogre, it has +6 to hit or a 50% chance. Around the 50/50 point, Disadvantage is at its best, making a difference equivalent to -5 on the attack. That means, if you cast Vicious Mockery on that ogre, which also has low wisdom to boot, you have a chance of about 70% for it failing the save, and that imposing 25% chance to miss, or 17.5% for the ogre to miss on its attack that otherwise could have hit. The attack deals on average 13 damage, so this will save you an expected 2.4 points, plus it will massively lower the chance to get killed by a stray, unlucky critial hit.
I think in total, it still is not quite making up for it -- 1.5 damage and 2.4 avoided damage is still only 4 points vs the crossbow's 5 points of damage, and the ogre is somewhat of an ideal application for Vicious Mockery with low Wisdom and a single, high impact attack. On weaker opponents, like goblins or hobgoblins, the benefit will be a good bit lower. Moreover, if you hit a goblin or hobgoblin with Vicious Mockery, you have no chance to one-shot kill it. If you hit them with a crossbow, you have a chance to kill them (a fair one too in case of the goblin), which means they will never get to hit you back or do anything else -- obviously a lot better than giving them Disadvantage. And many of your fights will involve larger numbers of individually weaker monsters, where the crossbow is flat out better.
1 Making Bards dump Strength is a common approach, because one of the major uses of Strength is melee attacks, and bards are proficient in Rapier that has Weapon Finesse and can replace Stength with Dexterity for attacks, for escaping grapples they can use Dexterity (Acrobatics), too, and they can only wear light armor, so their AC will benefit from having a high Dexterity.
There are relatively few other uses for Strength if you do not need it for melee, as Strength-based saves are rare, so it is a common dump stat for high Dexterity characters. You mostly need it for Strength (Athletics) checks when initiating grapples, shoves, or climbing and swimming.