Hiya.
First, don't sweat it. The 5e system is nice and loose...it can handle a lot of tweaking.
Second, don't coddle your players. It was their choice to put the focus of their group towards...er...whatever they have a lot of classes that focus on (Damage? Stealth? Spell-a-Kaboom!'s?). Because of this, they simply will have to think of how and when to attack a bit more carefully. They'll have to come up with ways to mitigate taking damage themselves. That's
their problem,
not yours.
Third, and this is going to be the hardest for the first session or two, you have to unlearn what 3.5 taught you. There are no "healing wands" in 5e because they aren't really needed; everyone heals up fully after a full nights sleep (Long Rest). After a 1-hour breather (Short Rest), they can use Hit Dice to heal up themselves...and
healing potions are more or less "mundane" items available for purchase at the local grocery store. Also, the first 2 or 3 levels of a character will FLY by. The Lost Mine of Phandelver (Starter Set), the very first encounter will net the PC's 75xp each (you need 300 to hit 2nd level). If/when they go into the next part (Cragmar Caves), they will wander out with 275xp each. Welcome to 2nd level guys! Anyway, point being, the PC's really don't "spend much time" at levels 1 - 3.
The key thing to remember about 5e is that it is based upon a solid, low-power base line. Slick play by players will yield significantly more success than having extra rules for mundane healing and a quiver full of "healing wands". I can not recommend strongly enough that you play it more or less as written for the first few sessions; I'm sure it will be quite the eye-opener...
^_^
Paul L. Ming
PS: There are no +4 or +5
anything in the game...+3 is the maximum, and that's reserved for artifacts and relics. In 5e, getting +1 shield, +1 armor and a +1 weapon is a
BIG advantage! Getting all at +3? Pure epicness.