Therapy can be be very taxing, even painful. I know that the pace and the time it takes to see results can be frustrating
I'm sorry that you had a setback. I hope that you are feeling better now and that your therapist treated you very gently, or gave you a break, for a while after that

I have been through therapy many, many times. At some points, I've only been able to afford to go once or twice a week because of the cost of copays, but I did very light exercises at home, and that was enough for me to get back to where I needed to be.

I think that twice a week is going to be just fine, especially since you have overworked yourself once already.