Pregnant after birth control

How hard was it for you to get pregnant after being on birth control ? I only see my boyfriend ( 3 years ) on the weekend because of school for me and work for him and I'm trying to conceive we have sex on my fertile days but nothing seems to be happening. We've been trying since the beginning of the year. I've been off of depo for 16 months now and I'm beginning to think I can't have kids anymore. How soon did you become pregnant after getting off birth control ? What should I do ?