trouble with getting pregnant

Hello everybody, I'm trying for some time already to get pregnant, but I'm little worried. I never get my periods on time. Sometimes I get it after 30 to 40 days, and sometimes 40 to 50 days.. Sometimes I even get it more than once in a month. I've read, that that could be a problem to concive. My docter even told me that I'm maybe not ovulating at all... And that I'm going to have a really hard time getting pregnant. I've used the pill for 2-3 years, but before I started with it my periods weren't on time. And now, after the pill is the same story. Is there anyone who can tell me something that could maybe chear me up? Somebody with same condition maybe who was lucky to get pregnant? Thanks