It sounds like its time to focus more on calories and less on meds. You have been stalled for months which means you have not been eating at a deficit. Logging calories and loading up on less calorie dense food makes more sense than just trying to add more meds. They are best used to help you move to eating a healthier diet rather than as the primary way to lose weight.
You are very active which is awesome and something a lot of people struggle with. You likely feel that your diet has been good but the lenght of your stall means that you are definitely still consuming too many calories. I would highly recommend a calorie tracking app and rigorous logging; really look at what you are putting in and don't just use their suggestions, they have been shown to be wildly off.
I understand looking for that appetite suppression and hopefully you can get that back but in the meantime, I would suggest really looking for less calorie dense foods and focusing on protien and overall volume. That should help some.
I would actually argue that this advice is not the correct advice in this context, someone with severe long term obesity struggling to lose weight on a very low calorie input. Who has stalled 2/3rds of the way to their goal on maximum dose tirz. Is it possible the calorie count of 1300 is inaccurate, yes people are in general very bad at calorie counting, but attempting to use conscious cognitive constraint of calorie input long term as a means to control obesity just does not really work, it can produce short term results, but much less so long term ones. Altering food types eaten is less of a bad idea, I like low calorific density high protein approaches, as it is easier to eat enough food to be less hungry while not consuming too many calories.
The only treatment besides surgery that seems to be able to make a substantial difference in severe obesity so far are GLP drugs. There is not a lot of research on what to do if stalled on maximum doses yet, but there will be eventually, and quite a few people on this forum have had much better than clinical trial results with combinations and higher doses. I find that they help me maintain my weight loss of 55% , but it is taking a tirz/reta/cagri combination to do it.
I am extremely skeptical of advice to increase calorie intake to increase weight loss in this context. This is just not really how bodies work. I do realise there are a few people online who have had success with this approach, but for me in a somewhat similar situation to the OP, of chronic adaptation to low calorie input and weight stable at 1600-1800 kcal/day, even 100kcal/day extra will increase weight.
If the degree of hunger is distressing , one option is to ramp up doses of reta faster, but doing this increases chances of more severe, more sudden side effects. The safest way to do it is split dosing so every 2 to 3 days or twice a week, so that if twice a week , you could go up 0.5mg of reta per dose so 2.5 twice a week then 3mg twice a week etc, so long as you slow down the increases if side effects or appetite suppression starts. But you need to look at glp plotter first. at least with smaller more frequent doses, usually it will only take half as long for side effects to settle down if you start getting them.
If you get to higher doses of reta and are still having major problems, you might be better off going back to tirz, with cagri added, or even some version of reta plus tirz, which seems to work for me. Or even just bump the tirz dose back up to 15 mg with the lower dose reta added on, and low dose cagri, which is essentially exactly what I am taking. I think this degree of polypharmacy with GLP's requires at least some monitoring , ideally medically, but checking blood pressure, lipids, liver function, renal function, blood counts and blood sugars at least is a good idea. And if diabetic especially if on other meds , very careful blood sugar watching.
One other thing is that sometimes people do experience increased hunger on starting reta, due to the glucagon agonism, which settles down after a while as the body adapts to it.
