Been trying to have a baby for 4 years, having trouble concieving?

Me and my husband have been married for 3 years (I'm 21 he's 22) we've been actively trying to get pregnant for 4 years, just having unprotected and keeping our fingers crossed. My mom tried for 5 years before she got pregnant and the women on my dads side have an even harder time getting pregnant so I'm thinking if there's a problem its hereditary. Anyways he's in the army and deploys a lot so after his next deployment he wants to go to a fertility clinic and see what's wrong, but I'm wondering if maybe I should just by those ovulation tests and have when I'm ovulating and see if that works before we go through all the fertility testing? He got me pregnant when I was 14 but I miscarried and haven't been able to get pregnant again sense. Don't some women who miscarry have trouble getting pregnant again?