Nightfli in the nicest possible way can I ask if your parents have any reason to feel upset at your pregnancy at 20?
Did you have plans, job, travel, uni etc that have now had to be shelved or postponed indefinitely?
Were they nice when you were growing up, kind? Or have they always been unsupportive?
It sounds like they are being horrible and unsupportive now and maybe they are!
But also maybe they expected you to leave home and make a career or whatever and they feel you are quite young to be a mum or they are quite young to be grandparents?
Maybe they feel you rely on them too much, or not enough!
As you will find out (when baby is older) parenting can be very hard. YES babies are hard but trust me older kids are harder in a different way! I expect your parents have some 'issues' around you becoming a mum quite young but I hope you can all work it out.
They will have to work this out themselves and it may take time.
You are living with them now, do they help you, do they give you reduced rent, no rent, do they pay for things? Try and find a way to make your peace with them, even if you choose to move out.
You may need their support and help later and I agree with someone who said, don't burn your bridges.