recently was facing issues, got my testosterone checked

i recently was facing issues having erections (morning or otherwise), and having hard ones when i do have them...

it wasnt probably a temporary thing, as such an episode could last 2 or 3 weeks at a time.. i would then recover, but the condition could return in a few months... had 2 or 3 such episodes in last 12 months...

so i got my testosterone checked out..

serum testosterone = 423 ng/dl
serum shbg = 28.65 nmol/L
S. FREE ANDROGEN INDEX = 51.3%

Do these numbers look OK for my age and fitness? How do i raise these numbers and do i need to?

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I am 27, and consider myself fit and healthy otherwise, and take no medicines except some multivitamins..

i was low in vitamin D (5ng/mL) and vitmin B (230 pg/ml) a couple of months ago, but had injections to correct that..