You are at 548, a average 26 year old level is 617 with a standard deviation of 170 .
So something like 65% of 26 years olds will be in the range of 447 to787.
So you are well within a normal range, but you can see how wide that range is. What is more important is how you feel. Fatigue, trouble concentrating, lack of hair growth (not scalp),& certainly hot flashes could indicate low T *for you*. If you were at the high end of normal before, 548 might be low enough to cause symptoms (but not too likely).
As long as you are feeling fine, I would not be concerned.
Jan, 1975: Right I/O, followed by RPLND
Dec, 2009: Left I/O, followed by 3xBEP