What Are The Signs Of Pregnancy?

I m 22 and my husband and i are very sexually active. Ive had our daughter 7 months ago, and was put on the depo and i bleed the entire 3 months so my doctor put me on the pill. I started taking it, and it went great, but i had to go back a month later for a pap before getting my year supply, well my doctore decides to change everyones appt because he was going on vaction so i was going to run out of pills before he got back so i had them to call me a prescrption in. I went and got it later that evening and when i got home it was not the one he put me on the month before and that was he last day before vaction so i started that pack so atleast id be protected. I continued to bleed that entire pack and when i went for my pap i explained how they messed up and gave me the wrong presciption, so he wrote me some for the pill i used first and started the pack and when i was suppose to get my period i didn t. I took two test which came out negative. now this time around for my period i got one morning and had slimy slightly bloodly discharge which i thought was the start of my period, but that was it. No period this time either. I just started my next pack and wondered could i be pregnate or could this birth control be causeing me to have a weird reaction?