This is still pretty inaccurate but a general guide for each frame (there’s still a lot of variance within each.) According to this at 5’4 and tiny frame (small) I should weigh 114. I’ve never been this in my life and I’m not underweight, I don’t have an eating disorder, doctors don’t say I’m unhealthy etc etc. Ideal weight is more than just frame… bone density and body compound (muscles and percentage fat) come into it just as much! Also age to a point! So yes according to this I need to gain and yes I’m quite happy to do that if it means losing fat and gaining muscle.
Personally I think people should worry more about how they look and feel and their body fat percentage rather than their weight.

