My girlfriend and I decided that we were going to get drunk one night with a friend and ended up doing so.. She's on Lo Loestrin Fe birth control and has been for 3 or so months. She started a new pack that night (active pill) after just finishing her last pack of in-active sugar pills I believe. She got sick two hours after taking it, but did not double up as she believed that she'd be okay that it had already digested in that short amount of time. We waited a few days before having unprotected sex (I do not remember how many, but I think 4 or 5) and seemed fine for two weeks, she began to develop tender nipples (not the entire breast, just nipples and only when touched in a certain way.) and we unfortunately Google diagnosed and have led ourselves into believing there is a chance she could be pregnant. She isn't showing any of the MAJOR signs of pregnancy (morning sickness, implantation blood, etc.) however, there are a few minor signs that could also be signs of side effects of birth control and there really is no telling. She has not gotten her period yet, it's due in a week and a half (possibly less.) However, it's been 13 days since the unprotected sex and that's the first time her nipples became tender. She's three and a half months into Lo Loestrin Fe, and have yet to have problems, however the normal side effects of the birth control such as light periods did not start until last month, so I think her nipple soreness could just be a side effect of the birth control.