You use whichever is higher for this Stealth check
To break down the rules from the PHB (emphasis mine):
Your game Statistics are replaced by the Statistics of the beast, but you retain your Alignment, personality, and Intelligence, Wisdom, and Charisma scores.
Your beast form's Strength, Dexterity and Constitution cover ability/proficiency checks for the wild shaped form, and your PC/Druid's Intelligence, Wisdom and Charisma scores cover the other ability/proficiency checks.
You also retain all of your (druid PC) skill and saving throw proficiencies, in addition to gaining those of the creature.
If the creature has the same proficiency as you and the bonus in its stat block is higher than yours, use the creature's bonus instead of yours.
If the creature has any legendary or Lair Actions, you can't use them.
For mental (INT, WIS, CHA) abilities, saving throws and skills you still roll with your own (Druid PC) stats + proficiency bonuses.
For physical ones (STR, CON, DEX), you choose the highest between your proficiency bonus and the beast's proficiency bonus, whichever is higher. (It is either / or, not and) and then add the beast's physical attribute.
Modifier if both I and the animal are proficient in stealth: 1 (Animal
Dex) + 3 (max. of 3 (My Proficiency Bonus) and 2 (Animal Proficiency
That result would be 4.
If like me your druid has the Resilient (Constitution) feat, this allows you to use your own constitution proficiency bonus instead of the (more often than not) weaker one of most beasts.
TL;DR: For mental abilitiy scores, you keep your own ability score. For physical ability scores, you take the beast's ability score: To those you add the proficiency bonus which is higher, yours or the beast's.