Blood levels of testosterone have a broad range when it comes to normal. Blood levels change in cis men as they age, and some Dr.s try to mimic that in trans men as closely as possible.
My level came back twice normal a couple of times on the androderm patch, and the dose was dropped. In the very beginning, I had to get my levels checked frequently while they were trying to get the results that were in a normal range and giving me the secondary sex characteristics I wanted. If you haven't had your ovaries removed yet, then it might be more challenging, but an endocrinologist will be able to figure it out.
Personally, I think that until your testosterone is stabalized where you want it and your Dr. feels is within the normal range, staying with an endocrinologist is a good idea. Family physicians, (some of them), are comfortable running levels and scripting T once you are stabalized.
sam1234