Check prices on monj.co.uk, you might find cheaper.
if you go mid way between 2.5mg and 5mg which is 3.75mg (45 clicks) in a 5mg pen you will get 5 doses out of your pen before it locks and within the 30 day in use window (inject on days 0,7,14,21,28). Your provider won’t advise or condone this so no point talking to them about it. Just tell them you skipped a dose (holiday, forgot, unwell) if they ask why you are only ordering every 5 weeks. This may help financially.
Focus on the more subtle effects Mounjaro is having on you blood sugars and cravings rather than the more obvious suppression/slower gastric emptying which may affect you HH more. Work with Mounjaro with plenty of protein, fiber for bulk, minimal UPF/sugar/sweetener/simple carbs, plenty of water - it really does make a difference to its effects.
This will hopefully help you stay on lower/cheaper doses for longer - I’m post menopausal, have done 15 months on 3.75mg, lost over 8st - I know that lower doses are not effective for everyone but also think some do increase without making the supporting diet changes first or until later.
Be aware of the risks with long term PPI use. I was on Omeprazole for 8 years and ended up B12 (nerve damage) and magnesium deficient (foot/leg cramps) and I worry what it has potentially done to my bones, no one ever told me it was a risk. Thankfully with the weight loss reducing the symptoms, and then being able to identify trigger foods (no more tomato based food unless I have gaviscon nearby!) I have been able to stop omeprazole and cope with occasional rennies and/or Gaviscon Advance now.