I had to tell my mom I was pregnant when I was 17 and It was the hardest thing I had to do. I would just come out and tell her that you think you might be pregnant because of how you are feeling. Moms can be hard to talk to esspecially when you think they are going to go nuts on you, but mine cried & said she would be there for me.
But you never know maybe you are not .I would wait to see if you miss your period then talk to your mom first.