You’re no stranger to the low Hb. Thirty years is a long time to be coping with that. Interesting that it started around 21. Did you have an illness, EBV or anything like that? Was it low enough to have you chronically fatigued?
Interesting about the weight. Usually as we age, it comes on whether we want it to or not! 😅
I found a couple of posts on Connect regarding people trying to gain weight. The site I’m giving you is actually entitle Weight Management; guidance on selecting proteins powders. But within the discussion are conversations with people wanting to gain for various health reasons. This is the link: https://connect.mayoclinic.org/blog/weight-management-1/newsfeed-post/guidance-on-selecting-protein-powders-shake-and-bars/?pg=2

I had issues early on during cancer and transplant recovery in trying to put some meat back on my bones. The dietician at the hospital was great with tips to fatten me up. What I found though is that I really had issues gaining weight for about 2.5 years until I was off all my meds! They must have had an impact on my ability to absorb or break down the food. Because no matter what I ate, I barely gained anything. Last October I was able to stop all meds and I’ve gained back 10 pounds with no diet change! So now I have to start cutting calories so I don’t go crazy in the other direction. LOL
Have you seen an endocrinologist about the inability to gain weight or a dietary counselor?