Starting to feel really scared..

Hey gals! Hubs and I are on month 3 of TTC and im starting to get so nervous that something is wrong. I ovulate the same time each month, my cycles couldn't be anymore "normal" at 28 days, and we BD every other day as soon as AF is gone, and 4 days in a row as soon as I ovulate. (Proven ovulation with temping and OPKs) last month we used preseed and I've been taking prenatal vitamins for almost 5 months now. Why isn't this working! I know it's not that long as some of you ladies have been trying much longer, it's just so frustrating to be young (im 24 and hubs is 26) healthy, and it's still not happening! Any other ladies with advice or similar situations?