Question/Your experiences?

Hey guys, last month my boyfriend and I became sexually active. We have been really careful, where he uses a condom (and throws it away and gets a new one if he thinks he puts it on wrong etc) and I haven’t missed a single pill for months. It’s been over a month since my last period but I don’t know if I should be concerned because ever since I started the pill back in August my periods haven’t been that regular (I use Lo Loestrine FE) and because we have been very careful. What’s the likelihood of actually getting pregnant when using a condom and the pill/can sex make your periods irregular? Also should I try to switch to a different pill to regulate my periods for peace of mind at least? Sorry any advice would be great, I’m just confused since becoming active was a big step for me and I did it with a lot of research/educating myself first.