Missed 4th pill during first week of pack

I started a new pack of Junel 1.5/30 combination oral contraceptives on the 21st of December. I was late to take the 4th pill of the pack during the first week (December 24th) by nine hours. I took it the next morning as soon as I noticed as I regularly take my pills at midnight before bed. I continued taking the rest of the pills as normal and have not missed since. My boyfriend and I have consistent unprotected sex and had sex a few days after the late pill. I am now 14 days past the missed pill and have been having stomach pains and what I believe is acid reflux for 7 days in a row. I have no other symptoms of pregnancy (mood swings, fatigue, vomiting, food aversions/cravings, heightened sense of smell, etc). I should expect my period on the 14th of January (one week from today). Should I be worried about pregnancy or do I just have a stomach bug or something else to be worried about?

Thank you in advance for your advice and wisdom!