I’m going to apologize up front: I don’t think this is going to answer your question. It’s a partial answer, at best, and while I hope some of this is helpful, it doesn’t present a complete build. I aimed to offer one, but basically, I came up empty: unfortunately, Paizo really doesn’t seem terribly interested in helping you to do what you want to do. There just aren’t any good options available. I realize that you don’t have particularly high expectations for what any given build can do, so maybe you’ll want to use this anyway, but I cannot in good conscience recommend much of what I offer below.
Basically, dagger-throwing is really, really bad, and dagger-stabbing is only slightly better because it’s easier to do cheaply. There are some exceptions (e.g. a fighter might be able to pull enough feats together to do dual-throwing, a knife master gets d8 sneak attack dice with daggers), but none that apply to you as a bard.
If you really want to insist on trying to make daggers a serious part of the character, though, here are the best options I can find for you:
Weapon Finesse—if you’re going to be both melee and ranged, you’re going to need Dexterity, so you might as well drop the need for Strength.
Blinkback belt—this 5,000-gp magic belt returns weapons you throw with it as soon as the attack completes. Which means you can immediately throw it again if you have another attack (e.g. Rapid Shot, BAB +6/+1), unlike returning for example (which would cost more anyway). This is without a doubt your absolute first priority as far as treasure and wealth is concerned.
Note that blinkback belt, being a belt, does conflict with the belts that enhance physical ability scores. First, I absolutely must recommend that you talk to your GM about fixing this, as it is a serious design flaw in Pathfinder: having physical ability scores appear only on belts is a massive tax on physical characters. Magic Item Compendium from 3.5 allowed every score to appear in multiple slots, and also made those kinds of bonuses freely combinable with “real” magic like blinkback (i.e. no 50% surcharge for having two things on one item). I strongly recommend that all games use that rule instead of Paizo’s. Paizo’s is insultingly terrible.
But barring that, yes, you do want enhancement bonuses to Dexterity and probably Constitution. Yes, that will make blinkback more expensive (7,500 gp)—and it is still worth it. Even if you have to bribe the party mage, or quest in search of someone willing to do custom crafting for you, it is still worth it. You must have a blinkback belt if you ever plan on throwing a magic dagger, or plan on making more than one ranged attack in a round.
Note that blinkback also largely obviates the need for Quick Draw, which you would otherwise need if you wanted to throw a dagger more than once a turn. That feat would still be somewhat useful, and definitely appropriate, but this character is going to be exceptionally feat-starved, so I strongly recommend simply relying on blinkback for multi-attacking, and not taking Quick Draw. You are unlikely to have multiple attacks available substantially before you can afford blinkback anyway.
Far Shot—note that range penalties apply for each range increment you meet, rather than exceed: that means that you take a penalty from range with daggers even if the target is just 10 ft. away. Any closer and they’d get to make an attack of opportunity, so that means that , you will pretty much always take those penalties. This feat halves those penalties.
Distance—this special weapon property doubles the weapon’s range increment (like the 3.5 Far Shot did; why they felt the need to nerf that feat, I’ll never know). It’s ludicrously overpriced as a +1-equivalent, but you’re probably going to need it. Between this and Far Shot, dagger throwing is almost kinda-sorta functional.
Finally, once you have paid the above taxes, the typical ranged-attack feats become useful to a dagger-thrower: Point-Blank Shot, Precise Shot, Rapid Shot, Cluster Shots, maybe Deadly Aim. Unfortunately, your ¾ BAB is going to be a huge detriment here, to the point that these feats are going to function poorly and may not be worth taking even though they are the best options you have for dagger-ing.
On the melee side, there isn’t really much to be done beyond Weapon Finesse: you don’t want to dual wield (and don’t really have the feats to do so in any case), and that leaves you with few avenues to substantially improve your dagger use.
If you could somehow tack useful effects onto your dagger attacks, that would be something, but unless your GM agrees to allow a dagger-adapted arcane archer, there aren’t many options available. Magus (e.g. eldritch archer) could tack spells onto dagger attacks, but only for magus spells, which doesn’t help you much as a bard, even if you multiclassed. Poisons could be perfect, except that they are terrible and not worth the effort. Sadly, I really do not think there’s much else available.
So ultimately, even with all of these feats and items, your dagger use is unlikely to be more than a curiosity, something to do when a fight is well in hand that’s marginally more interesting than twiddling your thumbs. Music and spellcasting will always be much more useful things for you to do, so this is really only after you’ve done all that and the party just needs to mop up.
As such, I would probably just take Weapon Finesse, equip a dagger, and call that good enough. But that’s just me.
Either way, your bard class levels don’t really come into play. They just don’t really have much in particular to offer dagger use, and the character you describe is, aside from the dagger thing, a pretty typical buffer bard—which is a fine thing to be. This is what the bard class is all about, after all, and it’s pretty... OK at that. Paizo, for reasons unknown, badly nerfed it from 3.5, but it’s still mostly functional.