Welcome dwilliams to the Board - it can be brave to post, and respect anybody that can.
It's pretty complicated your background here, just from what you've written. The side effects of initial steroid withdrawal/steroid adjustments in any case can often be weight fluctuations, whatever someone's diet: so that also needs to be taken into account.
If someone has a background of health concerns, and you have a number from this (and I don't know if there may be others in your history as well?): you may do best, if you've the cash or health insurance, to consult directly with the McDougall Program or a similar knowledgeable health provider. They may be able to take your care, and prescribe and give you directions. Please take then all the rest below then under advisement, bearing that in mind.
Mary's Mini is an option for optimum weight loss (see
https://www.drmcdougall.com/education/i ... ugall-diet) in the Program. Bear in mind people do often eat higher volumes of food for satiety because the foods are lower in fat and protein calories on WFPB - that's fine, and normal.
In going to WFPB, you'd generally be gaining glycogen weight and some water weight back: after it's unfortunate loss to the keto diet regime, and possibly the steroids. That's not unhealthy. If it is that, it's a sign actually of positivity. After initial restoring of the glycogen and water stores, if starting overweight you will get a longer term net weight loss, gradually over time down to your body's optimum weight. (As long as you don't overdo for your body the likes of high fat WFPB foods - nuts, seeds, avocados, soya, olives).
Given your health profile and illnesses, I do think it's really good idea for you, even if you can't afford to go to a formal provider, for at least a GP or nurse to monitor your baselines, if possible.
Try and obviously study as many resources too as you can as well on the McD site, which do include info relating to conditions you've had - in the Newsletters, the topics, as well as the YouTube videos with Dr M speaking on different areas will all be of long term help.
Good luck!
"All people are made alike - of bones and flesh and dinner. Only the dinners are different.”
Gertrude Louise Cheney