family vent. am I being selfish?

I'm 8 months pregnant and apparently the only one in my family with a valid license. On my days off of work I do not want to be driving people around but when I say no they act like I'm just the most inconsiderate person ever. 
I'm tired! That's all. And I have to waddle around at work 5 days a week. I'd like to be unbothered on my days off. I don't understand why grown people don't have a reliable source of transportation. It's so annoying. And it'd be different if I could say no without them throwing a fit and calling me selfish. I really wanna know who they're gonna bug when this baby is here because it won't be me. 😑 
I don't mind it SOMETIMES. But if you give an inch they want a mile. I am not a personal driver.