Is this normal?

ok so I recently posted this:

So yesterday I was on day 7 of my first pack of birth control pills, ortho tricyclen lo. I had protected sex with my boyfriend, then we had sex again an hour later without a condom, but he didn't finish. I was worried that there may have been sperm left in his pre-***, so I took plan b today, mainly because I hadn't waited more than 7 days before u***otected sex like planned parenthood told me. I went home and read online that you should wait a month after starting the pill before having sex without using a backup method (hence confusion, my worry, and the taking of plan b). So I will continue to take my birth control, every day and at the same time. I know my cycle's probably really messed up and my period may be late (next would be due February 5th, based on this month's which came on January 5, 2 days earlier than December's. I also took plan b the first week in November 2009).

I have now been on the pill for 18 days, and it's 2 days away from when I should be getting my period if I hadn't started the pill. I started getting cramps on and off all day today, and a few slight cramps yesterday, which would be normal, except I'm not supposed to get my period till later when I take my inactive pills. I know my period will probably either be late or not come because of taking plan b, but I was wondering if this cramping feeling was normal, like maybe my body is confused and thinks my period should come in a few days? It's making me nervous, I'm hoping they're not like implantation cramps or anything.