Antibiotics and period

Hi ladies. I sure hope someone can help. Me and husband have been ttc for 7 months. He is 38 im 31. I went to dr bc i thought i had break through bleeding so dr took urine sample and said i had an infection. She also checked thryroid and hormones which was all normal. I was on cd 14 at the time and my cycles range 25-27 days. Well the spotting lasted until period started which was 25 days this cycle and lasted 2 days normally 4 days and ive had 6 days of spotting afterwards. I just finished 2nd antibiotic. Could it be the antibiotics or something else? Im so worried i wont be able to get pregnant.