Did my antibiotics possibly delay my period?

I've taken antibiotics 3 times over the course of 1 month.
First, a z-pack for a sinus infection.
1-2 weeks after I finished the z-pack, I was given a 10 day supply of antibiotics to finish off the infection (I assume it didn't affect my birth control because I still got my period on time.)
My period is due this week, (actually, it should be here today), but I just started bactrim on Monday (6 pills), could that have delayed my period when combined with all of the other antibiotics I've taken? My boyfriend and I did have sex while I was on the antibiotic, unprotected, but still used the "pull-out method"...I'm starting to get worried. Please help.
Also, I've never felt menstrual cramps until the day OF my period...but due to my UTI it's hard to differentiate the feeling. My UTI has gotten better, but I'm feeling small cramps now.