Blueberry Been hitting the juice to much

Ok Blizz what gives? i come back after being gone a year and unlocked the vulpies seeing i had all that rep ground out before. so i get to level 100 and me little blueberry be started to die on 2 mobs pretty fast… hit level 117 and he cant even handle 2 mobs at the same time, i havent played a lock since mop? and that guy is undead, so i dunno what i doing wrong but hunters tanky pets are not squishy like this blueberry.

i have adjusted talents and spent 30k in gold upgrading the heirlooms for this little vulpy dude just to find out the tank pet and the lock is more squishy than a mage tank being the last man standing in a raid wipe. so i dunno what i am doing wrong but i am seriously thinking of shelving this little dude cause his blueberry be splattered into juice before i can even get 2-3 spells off and spend more time using the health funnel, kinda hard to wanna level him up when he dies this much. I hope this gets better with higher tiered gear cause this here sucks.