hello!

hello ladies, needing some advice. I've been very anxious and working myself up about being pregnant lately. I am on the pill and take it for 3 months without a period and then I get a period at the end of that 3 month time. I am 19 and have allowed my boyfriend to finish in me around 6-7 times and never worried about it. Around 2 months ago I took the one dose yeast infection medicine Diflucan, it is said that the one dose doesn't effect the pill but I am still worried. I took a pregnancy test that read negative but for some reason I can't get it off my mind tonight. Thoughts?