If u would've hit a vein, you would've felt it in a few seconds. Tingling of the lips, throat, face, the urge to cough, then you cough to clear the feeling and that is when it hits you! You feel like you're gonna die, can't breathe from all the choking, lightheadedness kicks in, you turn pail and depending on how much and how direct the shot was this takes longer to clear or just lasts a few scary seconds, my guess is you went through a vein, blood came out, and you drew that... It happens... Never forge the protocol, CLEAN AREA, PIN, aspirate and plunge slowly, why not try thighs and calves, you get a better grip on the syringe and you don't have to stand in an extremely awkward position in front of a mirror to pin on the glutes...