Yeah, eventually you’ll get there. I can usually take on most things one on one as a tank. Casters as a whole are pretty challenging, especially ones with lots of roots.
One thing I’d recommend as a prot tank is helping more in team fights and less on soloing. Prot warrior doesn’t have quite the same kit as say a blood DK or Guardian Druid for soloing. But they offer a lot with things like intervene to save a healer, dragon charge for disruption in a team fight, thunderstruck for rooting enemies (especially melee on your healers) and Morale Killer for 25% damage reduction for multiple enemy players for your whole team. Not to mention multiple AoE stuns and an AoE fear.
Might just be an adjustment in how you play and some practice to figure out what works for you. The most fun I had recently was in an Ashran with 48M health, we got the enemy team to the bridge at their base and I just kept dragon charging through them knocking half the team off either side of the bridge. I ended up with like 450m healing done and like 700m damage by the end of it as well and it really helped me figure when to bust defensive cooldowns and how to avoid pressing too far in and dying.