First pregnancy = miscarriage

Ok, so we did the BD for all of march after my period from 2/24-2/28, cycle was expected on 3/26.. No show, took a test on 3/29=BFN... 3 weeks later 4/17 still no AF, took a test =BFP!!! Excites beyond all explanation, we made an appointment for 5/6(quickest they could see us). Started bleeding on 4/26, went to dr. HCG=24, went back on Monday, HCG =4... Lost the baby. I'm healthy, no alcohol, drugs, don't smoke, I exercise... What the world!!!??? Then doc says wait 3 months before trying again??? Really? That's way too long, but I don't want to take a risk on losing another angel. Help! Devastated