Wow this must be extremly hard for u, i admire u, u are goin thro a lot. I felt scared about tellin my mum and im 19, in the end i didnt need to tell her she guessed, which was a hugh relief to me.
I know it is easier sed than done but u shud ell ur mum asap, she deserves to know, and she can be a great help after she gets over the shock of it all, and hey wots the worse she can do to u. Soutt at u abit etc etc. She may actually appreciate it more if u tell her now, rather than waiting even longer.
Have u told ne one about it at all, because if u havent it may be a good idea to tell a friend, ne one, just to tak about it.
At the beginin ur mother may be irational, and stop u frm seeing leo(i presume he is the father of the bay, sorry u mite have sed but i forgot), but she will come around, give her time. Jus grin and bear and break the news.
Good luck hun, i wish u all the best, and let us know how it goes.
bec x x