While 390 is clinically "normal." it may not be normal for you.
That's the trouble with testing for T.
If we had any brains, we'd all get a baseline done at about 25 and refer to that in subsequent years.
There are endos or GPs out there (although probably few and far between) who'd give you a prescription for some Testosterone.
I'd recommend trying Alpha Male for four weeks. If libido goes up, you know that your lack of libido was probably related to lower than optimal Testosteorne levels.
If it works, you can either continue on it, or seek out pharmaceutical T replacement.
However, having said all that, it is a little odd that it's so low. Any stress in your life? Do you train balls to the wall all the time? Soy in your diet? Alcohol?
Are you getting nocturnal erections? You could try the old stamp trick. Glue a string of postage stamps around your member before you go to bed.
If the perforations are busted in the morning, you know that you achieved nocturnal wood, which, while certainly not definitive, gives some indication of whether you're experiencing a pulsatile release of T in the morning.