As you say we can’t advise on dosage or whether you can stop your meds etc, but Metformin doesn’t really work like that - it’s a build up drug that stops your liver dumping too much glucose, when you say your numbers are dropping really low mid morning what numbers are you getting? I do keto and I’m on normal 500mg morning & evening, I get numbers between 3.8 & 4.5 around late morning - I eat my breakfast about 6 am, this is perfectly normal as allowing for my meters accuracy, plus being on metformin only you aren’t really at risk from hypos, your liver will do its job