Help! I'm so confused.

My boyfriend and I had sex, and the night we had sex I actually had gotten my period.

My period was normal, cramps, fatigue, and such. Than of course it went away.

It's been 12 days since than (my period ended the 6th), and of course Valentine's Day (the day I was fertile) we had sex without a condom, but he did not "finish".

However, since then I've experienced many symptoms of pregnancy; sore breasts, and terrible cramps. My mother also had noticed that my breasts have gotten larger.

However, this past Friday I drank. Quite a lot. To the point where I was vomiting, and sick.

Still... could I be pregnant? Could anyone help? I don't want to spend money on a pregnancy test for me not to be pregnant! Please help!