How old are you?
if you are 7/8 months pregnant now and have hid it from your parents have you atleast been going to the doctors/clinics?
If you are set on adoption, maybe when you explain it to your parents they will be relieved.
You cant hid it any much longer... you cant just turn around and have a baby next month and no one know.
You are only creating more trouble for yourself by hiding it. Mean or not yelling or not disapointed or not. You are now in a situation you cant just take back and your parents, scary to face or not: do love you unconditionally. and are most likely willing to help you in your time of need.
I would love to help you honestly making phone calls and everything with adoption. I am very good at research and contacting the correct people.
What is your boyfriends views on everything?