Confused!! Please help

KeVine
Okay so on4/12 I started taking the nuva ring. On 4/15 I took it out because I decided I wanted TTC. I soon got some bleeding on 4/18 to 4/20. I read that this bleeding was not my actual period and that I will be come fertile right after or up to two weeks later. Lately I've been feeling really neasuous and getting bad headaches. My nipples are kind of sore as well. I'm really confused. I took a pregnancy test yesterday morning and it was negative. My original period was supposed to be on 5/3.
Is there a posibility that I could be pregnant ? Was the bleeding I experienced in 4/18 my real period or just withdrawal bleeding? Please help!
Thanks