Hi Patience,

We'll have a better idea of what help you need as far as diet once you've had bloodwork but please do read your welcome message with regard to both the hay and concentrates that are safe for an IR horse.  With respect to weight loss, the Thyro-L will help jump start that but (much like people) the real key is diet and exercise.  For a horse that's overweight we recommend no more than 1.5% of their current weight or 2% of their ideal weight in hay and concentrates per day until their target weight is reached. 

In order to get that sorted out you'll need to weigh her hay (a lot of people use luggage scales) and not just go by flakes as not all flakes are the same size. 

As you're bringing your mare back into work you will need to be cognizant not just of the fact that you're rehabbing from an injury but that she'll need to be conditioned to handle any more intense exercise.   Did you do any kind of PRP into the suspensory?  Any shockwave or ultrasound treatment for it?  My gelding tore his right hind suspensory about 5 years ago now so I'm very familiar with the treatment and rehab protocols for suspensory injuries and bringing a horse back from one.  It took me about 6 months to get him back to his pre-injury level of fitness once we were cleared to do more than walk under saddle (4 months after his injury).

Given her age and the issue with her suspensory you may want to add PPID testing to the list of bloodwork just to rule out that she has elevated ACTH as PPID can contribute to issues with connective tissue. 

If you're using the pink Redmond salt be aware that the color comes from impurities and iron is just one of the issues with that.  It's really cheapest and most effective to use plain old table salt for NaCl.