Baby is growing too big 😶

My entire pregnancy he has been measuring big and growing big, mainly in 80-90s percentiles for everything besides one measurement. We just had an appointment and they took more measurements and he was 92, 96, 98, and 100th percentile. I'm 29 weeks on Wednesday, measuring at 30 weeks and 3 days and he is weighing at 3 pounds and 7 ounces. I have been diagnosed with gestational diabetes since around 16 weeks, has been diet controlled and all my numbers have been really good with the exception of a few when I give in to some cravings. The doctor said to test my meter and make sure that it is working properly and giving me the correct blood sugar levels. I can't check until I get the solution and that'll be tomorrow. If my meter has been correct the whole time, what could be causing him to be so big? I personally am not gaining tons of weight, even the doctor was not concerned with my weight. But the baby is and the doctor is concerned, so now I am concerned. I have an appointment next week to see him again but that's a week of worry. Anybody have any similar experiences or any knowledge 😶