This is my first time DMing a D&D game and I'm learning as I go. I'm running Tyranny of Dragons, and here's my situation:
Through a series of lucky events and other phenomena, the party is one level higher than the recommended level for this chapter–level 7 rather than level 6–and all difficulty has gone out the window. They are a larger than average sized group as well (7) and I am losing my players in combat as they don't feel the need to plan their next move. They have the, "We're not gonna get hurt anyway so I'll just hit something," mentality and it's certainly not what I want for my campaign. As with many other, I want my players to be challenged and entertained.
I've certainly learned my lesson with this as my first DM experience but I'd still like to salvage this campaign in any way I can. I was considering increasing the number of enemies in each encounter by a few and/or increasing their damage/defense by a few points as well but I'd like the community's input.
My question: how can I save this campaign and make my players fear the death of their characters again?