Why is my tolerance so damn high

i ,m18, 140lb take around 6 shots to get tipsy and like 10-12 to get drunk, usually take 10-18 a night for like maybe 6 months, usually jack, Jim bean, Smirnoff, or new Amsterdam so all 80 proof. I am on ivantabradine and flecainide with some serious heart conditions. Why is it so high and what can i do about