Hi Milli
I would go with much of donnellysdogs advice re changing pen and cartridges. I would go furtherand suggest you get a new prescription from a different chemist then bin what you have at home
Probably teaching you to suck eggs, but also
Keep the insulin you are using at decent room temp< 25 degrees dispose of in 4 weeks if any left, but presumably not.
Keep your spare insulin in a tupperware type of box, in the fridge, nowhere near the back, it's too cold, and not in the door as temp varies too much ( insulin doesn't like that) the box helps keep the vials safe if they fall out of the fridge. Any tiny crack in the glass will affect the strength. If you drop your pen on a hard floor, change the cartridge.
Do not keep a needle on your pen, it will affect the strength and also allow air into the cartridge, always do an airshot.
Yiur insulin will always work better given before food, preferably 15-30 mins before. If you don't know how many carbs you are going to eat, give some insulin and top up after.
Always check levels before eating and give a correction dose, aiming to bring your levels down to between 6-8 before next meal. If you arent going to eat at a normal sort of meal time, test and give a correction if needed.
Yes it will be more injections but good practise for a pump.
Lumps aren't always visible, have a look at your areas from all angles in a full length mirror, and have a good feel. Any thickened areas, or sites that you like cos it doesn't hurt, avoid.
Get as much help and support from your Dietitian as possible re carb counting and ratios
I really hope you feel better, and I know you have had a lot of suggestions and it probably feels like a load of work that you do not feel like doing, but if your levels are better, you will feel so much better yourself.