When is your period due?
Are you late, or are you just thinking you could be?
Get a pregnancy test now and test with the first morning urine.
Also, you said your mom was your age when she was pregnant with you, well although she will be upset about it, she will probably be the best person to help you through this because she's been there once.
Any parent is always upset at first, trust me im 18 and 24weeks and 2days pregnant, when i first told my parents back when i was 3 months or so, they were upset, but they let me know they were here for me know matter what.
Talk to your mom.
And take a test too.