It could be possible that you are ending the honeymoon phase. For some the honeymoon period can last 18 / 24 months.
You could quite easily be falling into this timescale.
If you're not aware of the honeymoon period I'll give you a brief summary.
At first diagnosis your pancreas is still working, not a t full capacity hence the symptoms and onset of your diabetes.
Once we start insulin, it takes a lot of pressure off the pancreas and it is able to function better, if what somewhat sporadically.
Your pancreas is still going to stop working eventually but this can take time ( 18/24 months in some cases ). This would be the end of the honeymoon period.
At this point insulin requirements will change and without correction your bs levels will start to rise.
Your 90 day average is slightly high and maybe due to your pancreas becoming less effective over time.
Apologies if you're aware of all this. It's only the first option to consider, but it's probably the best place to start.