I dont understand how this works and what to download for teens whatever I downloaded doesnt seem to be working.
You did read the post eh?
Did you install the insimenator(or squinzes mod ''pregwearanyoutfit?) and did you install the inteenimator?
With the inteenimator you make every teen pregnant, and they will use the meshes/outfits that come with the inteenimator.
If you want the bigger belly, make a sim teen with the skintone from the adult biggerbelly thread and use the meshes/outfits i provided.
Unfortunate sims will always revert back to the default maxis clothing, thats why you need the insimenator or squinzes hack to redress them.