I'm severely underweight and it's starting to get to me

I've always been underweight, my entire life. Even as a teenager. I've not been able to get above 125, and at the moment, I'm at 103. My BMI is 14.8. I know I need to eat at least double the calories, but I get nauseous if I eat too much. I'm also lactose intolerant and allergic to tree nuts, so it makes it hard to supplement with protein shakes. I tried the fairlife protein shakes but I think my digestive tract doesn't agree with monkfruit.

I don't know what to do. I'm tired of feeling weak all of the time, and having no energy. It feels like my bones themselves hurt. I have a doctor's appointment in a couple of weeks where we're going to discuss testing my thyroid, but I'm feeling like I'm damaging my body beyond repair at the age of 29. I already broke my leg once. I have an implant from it, and the surgeon was very concerned about my weight and that I might have osteoporosis.

This is mostly a ramble. I'm gunna go eat spoonfuls of peanut butter and try to make myself feel better for awhile. If you have any tips, please advise. Thank you.