The only way to find out is to take a test. You can buy one at any chemist, supermarket or poundland. The cheap ones are just as good as the more expensive ones. You can also get them done for free at a family planning clinic or your GP. You don't have to tell your parents.
When was your last period and when were you sexually active?
Your school nurse will probably have pregnancy tests too, and again, they are bound by confidentiality and won't tell your parents unless you want them to. So if you can't go to a doctor or buy a test, you could ask a teacher that you trust for advice.
You can go to a clinic and they'll help you do a test for free. It's all confidential. Sometimes you do just get random tapping in your belly from gas or digesting food, so don't be too freaked out. Still, it's always best to check asap if you think you are, so go to a clinic or to poundland and buy a test asap. Are your periods regular? If so, when was your last?
Take a test but could also be IBS, trapped wind which can pop and gurgle lower abdomen too, food already causing boating... If you've had unprotected sex or even on the pill, get a pregnancy test for peace of mind. X