Trying to get preggers

Hi so I was on the depo pervera birthcontrol Shot from March 2013 and my past shot was January 2014. How er ever 8 never had a period while on the depo pervera. My fist period was in august and it followed suit in September but two weeks after my schedule period that I had I had another one. At first I thought maybe it was implation but as time went on I've had two neg test. Vomiting, cravings, peeing every time I hear water, fatigue, weird vivid dreams, and even more emotional than normal. But time for my third period I didn't have it. Any ideas on what may be going on. My doctor did say it could take up to 18 months to become pregnant but I dont think I cam wait that long everyone I know is pregnant and having babies now.