Not new to BC but Period is Crazy.

So I've been off and on birth control since I was 16 due to dysmenorrhea. As I go to be around 22-24 I noticed I had more "good" periods than bad so I stopped taking the birth control. At 27 they started to get back again. I started taking a new birth control pill in January and my period has been weird since then. It either comes later than I expect, the flow is "off" compared to what I've been used to or it just comes very late. This month it is about a week and a half late. Granted I messed up my pills the week before my period was set to start and also had sex for the first time in a long time with my off/on so I am thinking all of this could be causing the problem, as this is not the first or second time something like this has happened. Not sure. Any input would be welcome.