Also trying any of these methods can lead to birth abnormalities, do you want to be responsible for that?
just think that if you are pregnant and you tried this then got rushed to hospital, your mom not only finds out that you are pregnant but that you are sick enough to try to do damage to the unborn child and possibly even screw up your chances of ever having children later on.
1 see a counsellor (or speak to a trusted teacher/aunty/friends mom etc)
2 get tested (are you really pregnant?)
3 arrange future protection (pregnant or not)
4 sort out what will happen to child if you are pregnant (termination, adoption etc.)
5 go to some practical parenting classes (you need to learn to prepare yourself)
at the end of the day your mom knows you've been doing it anyway, so she must know there is a chance that you can be pregnant. Yes I expect she will be angry, but that is most likely because she cares about you and wants the very best for you.
Don't take the stupid route, you've been stupid enough to have unprotected sex, now is the time to be sensible.
I probably have lectured you a bit, but you really need some tough love, but I have also given you the start of how to get things sorted, the real action is down to you