If you have never done anything sexual, then you probably do not have an STD.

Yes, there are many clinics that you can go to even if you are underage. You can look for ones in your area, call them up, and ask them for more information.

Bumps on the end of the penis are common. They are usually pearly penile papules. Pearly penile papules are not an STD, and they are not contagious. They are just a natural variation in penises. You can google them if you want to look at pictures and see if that is what your bumps look like.