Hi Tammie, sorry to hear you're having this issue, and thanks for reaching out!

Also, a big thanks to snojones for beating me to the punch with some great points and questions, all of which should be considered.

I do agree this sounds like it could be a set up issue. It would be worth taking it back to the guitar tech and describing the issue you are having. It doesn't sound right that the high E and B strings seem further off the fretboard.

What happens if you move the Am shape up the fretboard to around the 7th fret? Is it still painful to make that shape up in that position? If not, then most likely the nut might have to be cut lower.

Beyond that, snojones does bring up a good point that perhaps your fingers haven't built up calluses yet. Here are some tips from our GT blog on this topic:

https://www.guitartricks.com/blog/How-to-Toughen-Up-Your-Fingertips

As for the string gage question - I would say you can go as low as you'd like. It will (slightly) affect the tone, but it won't inhibit your ability to learn the guitar. Keep experimenting to see what gage works well with your hands.

Finally, always rest your hands/fingers when you feel pain. Don't push it!!

Hope this helps!! I look forward to our upcoming lesson!

Mike