As for a plan b, every time I try to bring it up, it just becomes very emotional and she accuses me of giving up too soon. I've tried to have a more realistic conversation with her, but she wants me to give it more time.
This is a huge no-go. My bf and I have been doing long distance for 2.5 years and we're closing the gap soon (internationally as well). We've regularly discussed worst case scenarios and plan B, C and D.
Her dismissing your feelings like that isn't okay. I know it's stressful, but it's not fair of her to just get emotional. YOU made a huge sacrifice and at the moment it's not working. You're getting depressed and you're suffering. Yes, it's only been 3 months, but if you're the one who's moved, it can feel a lot longer.
Especially since she works full time, often has work to do in the evenings, plus she takes fitness classes 3 nights a week.
Is she actually making an effort to take you along, introduce you to people etc.?