why is it so hard to get drunk?

ive had 3 standard drinks and feel nothing. mum says its an issue i can only get drunk when taking shots. reckons i should be buzzed by now. i can feel the most drunk ive ever been and not be hungover the next day. im 18, ftm, 2 years on testosterone, 174cm (5’8) and 80kg (176lbs). i feel like im doing something wrong but im not sure. thanks.