Personally, I don't think you should have been on Depo-Provera that long. I'm on it now but I don't plan on it being long term and am only on it now bc I don't have many choices but hopefully changing to something else soon. I've been told by many doctors that its not good as a long term birth control method because studies have shown that use of two yrs or more may cause irreversible bone loss and/or early osteoporosis in women (besides its other serious side effects). I'm not trying to scare you but instead, make you fully aware. If I were you, I'd go get a test to check bone density and make sure thats okay before considering bearing a child.
Now on to getting pregnant, after you've checked all that and made sure everythings okay...Depo-Provera varies in how long it takes to get out of your system in women. There's really nothing you can do about that. Some may get pregnant right away but it can take even up to 18 months before you can get pregnant. I'm surprised none of this was discussed with you by your doctor.
Now, just be patient. Stressing or getting desperate won't help matters at all. If after a year, you are still having problems with getting pregnant...I'd suggest you and your husband get checked for any fertility issues from both ends. If both of you are fine, then time is the only factor...just be patient, wait until the depo is completely out of your system and continue to have sex but actually enjoy it. Don't find it exhausting and stressful. Things will happen when the time is actually right, not when you think it is.