Hello, and I hope I can help you today. No matter how you feel, if you have had a negative pregnancy test and a negative examination, you are not pregnant. Furthermore, a mild antibiotic like Amoxicillin would not decrease the effectiveness of the pill, so you were protected against pregnancy during that time. Many women experience symptoms that are commonly associated with pregnancy such as bloating, breast tenderness, mood changes, spotting and nausea when they have irregular menstrual cycles because the hormonal imbalance that caused you to miss your period causes a buildup of hormones in your system similar to pregnancy. In your case, you were also taking birth control pills at some point, which can also have side effects similar to pregnancy. Your symptoms will likely go away once you start your pill-free week. Women can have irregular menstrual cycles for a number of reasons, like some medical conditions, weight loss or gain, travel, and stress. The stress of worrying about pregnancy can also affect your cycle. At this point, if you do not desire pregnancy, I recommend you restart your pills and take them as advised. As long as you do not miss any pills, you should be protected against pregnancy. If you experience bleeding while taking your pills (called breakthrough bleeding) do not stop taking the pill, as it will still be effective in preventing pregnancy. If you continue to bleed at the wrong time monthly on this brand of contraceptive, you may want to speak to your healthcare provider and request to change brands. I hope I was able to adequately answer your question today and that my advice was helpful. Best wishes, Dr. Brown