Period

Hi ladies! I have a question about my birth control and period, but first I a little background for my question.

I am 18 and I started birth control pills in June of 2017. Not for sexual purposes, but because my periods were SO bad that I usually missed a few days of school a month because I just couldn't walk because I was so sick. Well the first few months were a little rocky because of getting used to it, so I was spotting just a tiny bit between periods and had days where I felt awful. But, my period always came on time. I have 4 inactive pills and up until this month I've started either the night I take the first or the night I take the second pill. (I take them at night.)

Also, my period pains haven't been bad at all. I mean sometimes I feel a little bad, but unless it's a migraine, I'm able to do just about anything with hardly any problems.

Now, I suppose I am sexually active, but not having penetrative sex. Just some oral and fooling around (fingering and hand jobs). Just to be careful, my boyfriend ALWAYS fingers me and everything BEFORE I do anything to him just because precum and cum can cause pregnancy and of course neither of us want that so we're super careful about it.

Last month, I did not start my period until I took my third inactive pill. My period was a little worse than it had been since I started, but I figured maybe it had to do with stress because of exams coming up and a busy work schedule. This month, I'll be taking my third pill tonight. I've had PMS symptoms since Christmas eve and most of it was a couple of pimples and moodiness. I thought I was going to start last night because I took my second inactive pill and was having awful cramps and ended up puking because of how sick I felt (worst symptoms I've had since starting the pill). I still haven't started my period yet but I'm really confused on why they're starting later and why my symptoms seem to be getting worse. I've had no stress since exams (beginning of December) so I don't believe that's making me feel worse. Has anyone else experienced this or have any theories on why this is happening?

Thanks ladies!