@SpunkyKhakiScroller suppression, or even the desire for it is very individual. I have not had any significant suppression since the early weeks of taking Mounjaro. What I do get is no obsessive food noises or cravings, as long as I pay attention to what I eat and don't eat too much sugar/carbs. Or if I eat a large meal and eat mindfully, I lose interest in it and I make the choice to stop eating. This is enough to help me stay in my calorie deficit, but I need to work with it too. "Suppression" for many people does not continue past the early weeks, so have a think about what your expectations are from the medication. Some rush up the doses chasing that suppression they experienced in the first weeks and before they know it they are at 15mg and nowhere to go. If you are on this thread with >5st to lose and a longer journey than most that might be a difficult place to be.
Regarding off license use. There are some things you can do which may break the prescribing guidelines but are minimal risk.
The 5th dose in the vial is the exact same medication as every other dose. It would also be within the 30 day discard rule if you inject on days - 0,7,14,21,28. The only new risk introduced is using a syringe and the hygiene around that.
Adjusting your dose down using clicks is minimal risk.
Injecting, regularly, more than once a week is an unknown risk so I don't do it. What I would consider doing, as my provider recommends this if effects of current dose are wearing off towards the end of the week, is injecting every 5-6 days instead of 7 temporarily until the end of the current pen.
If you are getting no effects for the last 10 days (not just no suppression) that doesn't sound like it would help you.
If you want to increase your dose from your 2.5mg pen to 3.75mg then you can do that with 90 clicks or 0.9ml. I assume you don't have a syringe to do 0.9ml so you would need to do 90 clicks over two injections, replacing/repriming the needle for each injection. This again is minimal risk as you have done your 2.5mg for the minimum 4 weeks, and you are injecting less mg that the next dose up. As this is your 3rd dose you should be able to do this without the pen locking. There will be significant liquid left in the pen which you could inject next week using a syringe. Let us know if you want links to suitable syringes for next week.