Firstly let me so I am so glad you have your little dog, they make such wonderful companions, sometimes better than my partner (shh don't tell him, lol) I have 2 tiny puppers and love them to bits. They really help more than people realise.
I am so sorry you feel the way you do. I use to love in the city and loved it, moved to a small town, hated it, moved back to the city, realised I hated that more and moved back country.
Right now you are going through a major change, understandably it's all come as a shock, and feelings of being homesick are not uncommon, especially if things are so different.
I feel for you that you find it upsetting that you can't take your little dog with you like you were use to. Sounds to me like she was more a support for you to go and do things and to longer have that when you go out must be so hard.
I know my puppers are more support than anything, they're teeny, so usually I hold them in my arms when in dog friendly places and I find their tiny bodies soothing. I also like to think I'm helping them with their aversion to strangers, but alas, I don't think so. At least they bark these days, unless a stranger comes too close.
You mentioned the GPs you saw were rather rude, how unprofessional also very bad practice for them to reduce your meds without knowing your full history. Is there any other GPs you can see? Even if it's a little travel time.
I hate seeing new GPs, I had one when I moved here refuse to give me any anti anxiety meds when my dad died because he thought I was some sort of addict. I never went back saw another GP got the meds I needed used them to get me through and that was it. I was actually quite offended at being referred to as an addict.. thankfully I now have a GP who is wonderful.
I really hope you find something to help you out of the funk you find you self in, I can only imagine how it must be making you feel, go easy on yourself though big changes always take time to adjust to