My girlfriend and I had protected sex 5 weeks ago. It was a day after her last period. We have had sex a few more times since then. Before 4 weeks ago, it had been 6 months since she had sex. Now her period is late and she's feeling sick. She has recently started nipple stimulations to have larger breasts. I know that stimulations can induce labor, so could that combined with a lot of recent stress, the sudden sexual activity, and a common cold or the flu account for the missed period?