Am I being mean keeping my dog

I rescued my dog about 4 months ago and she is just absolutely terrified outside. We don’t know her past but she is now to the point where half the time I take her out she doesn’t go to the bathroom and is just terrified and trying to get back into the apartment (we live in a big city). I’ve had to go back on my own anxiety/depression medication because she makes me cry every single day and I feel like an utter failure and wake up with anxiety attacks everyday. We’ve done tons of training, us and with a professional, and she’s on week 1 of anxiety meds (I know these take a while to kick in but who’s to say if they will even help). She’s still nervous in the suburbs but was so much better than she is here in the big city. It’s been a few months and I feel like she’s getting worse, not better and I just don’t know what to do because I’m starting to hate my life and the idea of rehoming her is awful because she’s the perfect dog inside and I love her but I can’t tell if this is worth the pain for both of us