Hi @
Chloesnavy
Sorry to join this post so late - but I had exactly the same issue; taking insulin becomes so routine, it's easy to forget whether you took it.
I got the Timesulin cap, which has been mentioned above, which is great for telling
when you last took your last insulin - however, there have been a few times where I've taken my insulin and doubted exactly
how much I'd taken. I found a simple way to resolve both issues - now, after I click the appropriate number of units, I just take a photo of the insulin pen with my phone, right before injecting - so if there's any doubt, I can see exactly when I took it, and how much. Hope that helps!