Pregnancy & birth control help....

I have a couple questions & I hope I'm not the only one out there that has the same problems I have...

I have been trying to get pregnant for over s year now, & nothing is working! A lot of times I feel like I finally got lucky & it just doesn't happen.. that's really a big disappointment... anyway. I possibly have endometriosis & my doctor told me the only way to treat it at this moment is to do birth control. So he put me on the depo vera shot & that was literally hell.. it made all my pain worse than normal & it really bothered me that me bleeding as much & as for long as I was, is apparently normal... I also don't get my periods normally I never have...

How long does it take to get pregnant after taking depo vera?

Am I able to get pregnant due to my medical problems such as my stomach issues?

What am I doing wrong that it just isn't working?