why do you think there's no way you can get pregnant? that is pretty foolish, unless you've had a hysterectomy, which at 19, i doubt, you can get pregnant just like every other women in the world. pulling out does not prevent pregnancy at all. sounds like you're pregnant based on your symptoms (and i am assuming you're not trying since you said "there's no way you can get pregnant") so if it's negative you might want to start being responsible.
I'd go ahead and start getting a baby's room ready if you continue with this activity, eventually, you're luck is going to run out. If you're ready to be a parent, you're doing everything right, otherwise, you'd best get on the pill, or start using condoms and foam religiously.
If you're trying to get pregnant, your method is pretty good. (My mom got pregnant five times using the rhythm method.) Why not take a home pregnancy test? It would probably be effective by now, as you could have been pregnant from one of the times he pulled out.