Insulin resistance is a problem mostly found in T2 although it can be a problem for T1's also. Diabetes is high blood sugar levels caused by insufficient insulin levels. In T2 its frequently caused by your body not using its own insulin effectively. There might be an abundance of insulin (at least in the beginning) but due to insulin resistance there still isn't enough insulin to get the job done.
In T2's with insulin resistance high doses, such as the ones you describe, are common to overcome the resistance. There are lots of things one can do to reduce insulin resistance. If one is over weight then loosing a few pounds can help. Exercise is a great way to reduce resistance. And following a low carb diet can be a good way to reduce those high insulin doses. Those are the big three for T2 and a combination of those three things is what is generally needed to get T2 under control. In T2's such as myself the body's ability produce insulin is destroyed or reduced over time by overworking the pancreas thus the need for insulin. I suspect that's true for you also. If that's the case treatment becomes more like T1 treatment.
In T1 insulin resistance is not as much of a problem and the opposite is true for a lot of T1's in that they can be quite insulin sensitive and need very little dose wise to control their sugar levels. They always need insulin since their diabetes was caused by an autoimmune reaction where their body has attacked and destroyed all or nearly all of their insulin producing cells.
Type 1.5 or LADA and adult onset diabetes as its also called is a form of Type 1 diabetes that started later in life. It is T1 diabetes the only difference is when it began.
You say that you never see low numbers and always run in the high 200 to low 300 range. I want you to know that you can with the right treatment plan and a lot of work. The hard work is worth it because lowering blood sugar levels greatly reduces the complications you are likely to experience. If complications have already started then lowering BS can reduce the severity. And on top of that you will just feel better.
Your are in a good place to learn. I was frustrated also when I joined TuDiabetes but I became a daily visitor. There are so many people that can teach us so much here. Things like low carb eating and counting carbs so that insulin dosing makes sense and gets the job done. I hope that we can help make thing less frustrating for you.
Gary