Congrats!
Tell your Mum, My Mum always said that I had to tell her even if I wasnt sure I was pregnant! She likes to know everything!! But I know she also wanted to know so that if anything happened she could be there for me.
She got the shock of her life when I DID tell her I was pregnant and was even more shocked when I wanted her advice (I figure I turned out fine so whatever she did 25 years ago must have been right!) (and then for the slightly more sensitive/contriversal/things have changed type issues I hop on Bellybelly.

GOOD LUCK! I figure it is a natural thing being pregnant and we can only do our best, if we stress though it is bad for the baby so just relax and let your body do it's thing.