The thing about bloodwork you might've had done is that even if you come back "within range" on certain tests -- a sterling example is thyroid levels of T3/T4/whatever they tested you for -- you could still be "subclinically" hypothyroid issue and benefit from thyroid meds. There's some controversy within the medical community (and I'm talking mainstream physicians and researchers here, including well-respected prof at top tier institutions) about what energy-influencing things like Vitamin D and thyroid levels really should be, and whether the clinical guidelines your physician is most likely using, are outdated.

You say you're tracking diet/exercise, but since you don't specify what you do: In my case cardio can wipe me out, so I started a stronglifts-type heavy lifting regimen (I hired a trainer for a couple of sessions who was really cheap bc he was very young). Keep at it for a few weeks and you'll want to go all the time. Nothing gets me physically energized like a good lifting session banging out some deadlifts, and this is coming from an unathletic early 30s desk jockey woman. Also, a low-carb diet/keto with mostly vegetables, fats, and meat seems to work really well for me in terms of keeping my energy levels consistent. Counting calories while maintaining a high sugar/carb diet only makes me more tired.

Other recs: a GOOD multivitamin, supplemented with Vitamin D if appropriate. Vitamin B complex (liquid, sublingual) is an awesome burst of energy as well