Just don't know what to do😟😪

Rebecca
So I'm 20, my boyfriend is 23.
We are trying for a baby.
I've been off the pill since December 2015, used condoms since, had normal periods for the past few months, but the last mont and this month, they're 20 days from the start of one to the next. 
Why can't I get pregnant?😩😩
****EDITED* - we aren't using any protection and haven't been for the past 2 months***