DarkCrisis
Let her cook.
funny, in the newest campaign, sure we are 3rd level now, the DM is wiping floor with us, every fight, at least 2 out of 5 PC are rolling death saves, in one fight we were several times at 4 out of 5 out. luckily not once were both healers/casters out.
after every fight we look like we went 12 rounds with Mike Tyson in his prime.
Without knowing how many enemies / CR your DM throws at the group I can't really respond. But via the DMG standard battles aren't that rough. Even Deadly is kind of joked about. Not to mention official 5th ed adventures generally being a cake walk without the DM changing things up.
I've been running the Dragonlance 5E adventure and if I run the battles as written generally next to no issue in the battles. When I doubled the monsters, then they actually had a fight on their hands.
The DM can always set the rules aside and throw whatever he wants at the players. Can't really say that's what WotC / 5E was going for though. If they did they'd make the official adventure battles a bit harder.