Maybe, rather than try and tell your mum first, you could just say to her that you need to talk to someone and ask her to set you up an appointment? If she acts disappointed - which she might, because she is your Mum and I am sure is really concerned and wants to know all about you - you can reassure her that you will tell her once you have talked to someone and got your thoughts straightened out. Would that be easier than trying to explain to your Mum about things you are not really sure of yet?