Did I mess up my cycle?

I have an 18 month old and I just started going back to work. I'm also currently on birth control, but since I started work I've been having trouble remembering to take it, especially since my boss doesn't give me a consistent schedule. So I took it for a week then forgot and bled and so I waited and started taking it again and after a week I messed up and forgot again, so I had another period. So I decided to let my body go through a normal cycle and I would start again with my next period because it just seemed like alot of bleeding in a short amount of time and I was nervous I'd forget again. Anyways now it's been a month and a half with no period and my natural cycles are consistent. I took a pregnancy test the 16th of July and it was an obvious negitive. So now I'm just wondering if I'm pregnant or if I messed up my cycle. I have no symptoms of pregnancy or my period so I'm at a loss.