Penis is veinier,notice sometimes hourglassing when cold and when semierect(never when fully),weaker erections with premature ejaculate,a hard-all over flaccid penis.no lumps located.twitching and discomfort sometimes in perineum.16y/o,what is this?

It is abnormal. You should be examined by a urologist.

If you can have a normal painless fully erect penis then there is nothing wrong. Prominence of vein is normal. Cut back on your masturbation/ sex a bit and eliminate any porn. Slowly your other symptoms will get better. You are young and from your description nothing seema to be organically wrong. Good luck