I would suggest you get a copy of Taking Charge of Your Fertility. It is a great book that explains how your body works and how to help you get pregnant or keep from getting pregnant. It explained things to me no health class ever had or pregnancy website, etc.
I was about 6ish weeks along before I felt any symptoms and boy did they hit with a vengeance. Morning sickness that was actually all day long sickness.
I do know the timing for everyone isn't the same but having a baby at 21 is still very very young so you guys don't have to rush. Enjoy being married just the two of you guys for a while...this is what helped cement my marriage, was having a few years just the two of us before we had kids. We now have two and will celebrate our 21st anniversary later this year.
Get the book and take another test in a few days...or even today if you want to test they are super sensitive (well the ones that detect pregnancies before you are even late) the dollar store ones work good you just have to wait until you are actually "late".
Good luck!! and don't rush, children are forever...I can't imagine being my age now and already having kids in college...and I would if I had started at 21.