I think Im pregnant. Any alternatives?

I had sex about a month ago with my boyfriend for the first time and we didn't have any condoms and were a little scared to buy some, so we used a grocery bag. I don't know if he ejaculated inside or not, but when we were doing it, apparently I just started my period. Every sense then I've been feeling scared that I could be pregnant. So far, I feel bloated, but that could be anything. I suddenly felt overwhelming gas today. My breasts aren't swollen and I don't feel dizzy, but my brain is pulsing. That could be from my lack of antidepressants... I'm scared I might be pregnant. My period stopped about a week or two ago and I'm a little scared even now but I keep telling myself I couldn't have gotten pregnant by then. I'm 15, and I don't want my parents to find out I had sex or am possibly pregnant. If I get an abortion, or an abortion pill, I don't want to have them find out and I don't have any money to pay for it... Is there any alternatives?