so FYI for this time around it is very illegal to force any girl into an abortion even if she is a minor! so just let ur mom know that this time if she tries you will inform the police (even if u really won't). so just tell them, i suggest the two of u sitting all parents down and telling them, maybe not all together, but u need to tell them soon so u can get into a doc and start ur prenatal care.....
GOOD LUCK!