TRT QUESTION

Hey I have attached results of some bloodwork I had done. Trying to convince doctor to get me started on something. Am 48 and main symptoms are low libido, lethargy and poor gym performance. My doc keeps saying that my free test is within range although on low end. My serum test as you can see is below the range. I am a dumb ass but still confused as to which is most important regarding TRT. Any suggestions or info would be appreciated. Ready to start feeling good again. As side note, I maintain a lot of muscle at 235# 14%bf and this adds to my docs thoughts that levels are fine. Can a person maintain a lot of muscle with low test? I guess I know the answer, but curious if thats normal.

Thanks for any help in advance