aww hunny how crappy they are!!!
if it were me i would say to them its my baby and i'm keeping it, contact the council and tell your mum that if your not allowed to bring the baby up at home then you would appeciate her writing a letter to say she's chucking you out and they will put you in a hostel maybe up to a yr and then give you a flat of your own. and as for nanny speaking from a professional nanny myself (although i do not do it anymore) you get a job and take the baby with you
i know its easier said than done and really does depend how 'strong' you are but only you can decide if you want to and can handle doing all that.
when i took over from a nanny who just found out she was pregnant she then got a job down the road when her little boy was 6months old with a family with 5 kids, but 4 were at school all day she looked after her baby and their 2yr old.
my DH's cousin got pregnant (21) her mum and dad moved to surrey and chose not to go so she got a letter from her mum, was put in a hostel at 7months pregnant on her own and stayed there till lil one was 8months old and is extremely happy with her new flat
hostels were clean and comfortable. its more like a bedsit but you get everything you need and might find other girls in the same situation so will make friends along the way
good luck whatever you choose to do xx