Terrified I Could Be Pregnant?! And I'M Only 15????

Okay, so my boyfriend and I have only had sex once, and that was on Tuesday, Feb.5th. We used a condom, and I'm going to be on birth control soon. But he told me the condom broke, and now I'm freaking out that I could be pregnant, even though he pulled out but he said that he came a little. My last period was Jan. 21st, and I didn't want him to worry so I told him that I had my period. I feel terrible for lying to him, but I didn't want him freaking out and worrying about me. when would I be able to take a pregnancy test, and when would the first symptoms begin to show if I was pregnant? I would love to have a baby, but not yet. He's a junior in high- and I'm only a freshman, so we're nowhere near prepared for a baby. I know..it was a stupid mistake, and I just really hope that I'm not pregnant. So when could symptoms start to show, and when should I take a pregnancy test? Thanks :/
~Alexis <3