my dog pees inside but not outside whatsoever

hello all. i need help so bad. i have had my new puppy for about 3 days now, she's about 5 months old id say. she was given to me by someone i know, along with a kitten. i have no idea on her previous house training, im sure she was potty trained to an extent, (i'm hoping), but she seems really good with her leash habits, never barks except when outside, etc. and she's learned so far in these 3 days which rooms she can't go in. i feel i'm doing a good job of training her on other things, but i am at such a loss when it comes to her potty habits. she pees and poops inside, which i would totally be fine with in the meantime of training her, it's part of the learning process, obviously i am punishing her for the inside mistakes. the problem is she doesn't potty outside. she has not gone to the bathroom outside once in the many times i've walked her. i don't know how to reward her for peeing outside if she just doesn't do it. she's been an easy to train dog so far, and i think she would pick up, but she holds it when she's outside and lets a huge puddle and dookies out inside. it's driving me crazy. i'm in college, so i don't have long days, and im trying my best. she gets at LEAST an hour of outside time, probably closer to 2 hours. i walk her right when i wake up and after i clean her pee, right when i get home from school/whatever im doing, and before bed, each for at least 20 minutes, usually 30-40. we have an okay routine for now. then we'll come back inside after i give up on her peeing, plus i have other stuff to do like homework, cooking, blah blah. and then there's a huge puddle again in the living room.

i'm going insane, is there a reason she's holding her pee? could she have a medical issue? she very badly injured her hip with the previous owners and was never taken to the vet for it, she recovered on her own, could that be a possible issue? is she doing this because she hates me and wants me to go to the asylum?

i ask here first because i don't want to go to the vet just for them to say that she's just a puppy, i don't have enough money to be told that in a non emergency. if it is possibly an issue i will absolutely go, but i think i just need to be told by other people.