My mom found my birthcontrol pills, she freaked. What to do?

Good for you for taking precautions. Your Mum should be pleased that her daughter is mature enough to take control! Explain to her that there are 22 year old girls out there (me!) that weren't careful like you and became mothers at 17 years old. Your Mum will get over it! She just doesn't want her baby growing up so fast. Say you are sorry she feels that way about it, you love your boyfriend and you are being safe. Give it time, she will be okay.