Amoxicillin dosage. Antibiotics revew.

My period started late, could I be pregnant?

I take birth control pills. I had to go on the antibiotic Augmentin for 10 days due to cat bites. During these ten days, I used my birth control pill, but the sampling method, and if antibiotics do not work. Now my period is 4 days late, which has never happened before. He has just begun, but it is very light. Around this time my period usually stop by. I took a pregnancy test and it came out negative, but I also noticed on the package that expired six months ago. What is the possibility that I got pregnant using the withdrawal method and be in contraceptive pills while taking an antibiotic? Thank you for your help!

Antibiotics decrease the effectiveness of BC pills, I just read in my pills

Buy Cephalexin 1.79$ Cephalexin is an antibiotic, used to treat infections.

Buy Amoxil (Amoxicillin) 1.52$ Generic Amoxil is used for treating infections caused by certain bacteria. It is also used with other medicines to treat H. pylori infection and ulcers of the small intestines. Amoxil is a penicillin antibiotic. It works by killing sensitive bacteria.

Buy Minocin (Minocycline) 2.96$ Generic Minocin is a tetracycline antibiotic. It is used to treat many different bacterial infections, such as urinary tract infections, severe acne, gonorrhea, tick fever, chlamydia and others.

Buy Amoxi-Tabs 0.96$ Amoxi-Tabs (Amoxicillin) is a semisynthetic antibiotic with a broad spectrum of Activity, providing bactericidal activity against a wide range of common gram-positive and gram-negative pathogens.

Buy Noroxin (Norfloxacin) 0.88$ Generic Norfloxacin is an antibiotic in a group of drugs called fluoroquinolones. It is used to treat bacterial infections of genito-urinary tract.

Buy Avapro 1.57$ Avapro is indicated for treatment of high blood pressure. It is also used for treatment of kidney disease in patients with type 2 diabetes.

Buy Augmentin 2.31$ Augmentin (Amoxicillin/Clavulanate) is an antibiotic that is used to treat different types of infections.

Buy Biaxin 2.10$ Biaxin is a macrolide antibiotic, which is indicated for treatment of infections caused by certain bacteria.

Buy Trimox 0.82$ Trimox is an antibiotic which is used for treatment of infections caused by certain bacteria.