Could this make me miss my period?

ok so i was 10 when i had my first period..always normal and right on time and i took birthcontrol since i was 14 to 18 on and off and completely quit 6 months after my 18th bday..had my first baby at 20".which was 1/3/11! about a month later me and my husband had protected and condom broke...and took the plan b pill..and as soon as my period started i took bc for about three months and my insurance dropped me in april and had one pack of bc left and took it like regular..i had a period in june but not this month and ive been due since the 10th or so...and well my husband and i have had all protected and was curious if all this having a baby and taking antibiotics 2 weeks ago messed me up?? all that i have read hasnt made a whole lot of sense (due to my situation) so can someone help me out? we can not have another baby this soon and i doubt im pg but would also like someone elses opinions and ideas! please help thanks