I Messed Up My Birth Control Cycle. Any Suggestions

I use Nuvaring birth control . In january I got off my cycle for awhile but my boyfriend and I used condoms. We regularly use condoms when I m on my birth control just for cleanliness reasons. I was supposed to put the ring back in on the 7th of january but i ended up not putting it back in til the 20th which threw off my cycle. I was supposed to get my period on the 20th and I ended up getting on the 9th of february (which is correct with the new cycle). my boyfriend was concerned that I should have waited til my period began and put the ring in on the final day, like I did when I first started. But I m scared because this is my 2nd day of my period and I had a very bad headache and very painful cramps. When I pulled my tampon out there was two big chunks (i ve never had chunks before) of bloody tissue. I don t know what they are...I m so scared it was some sort of fetus or that I m shedding too much of my uterus. I m 18 and have been on birth control since July 2009