Am I playing heavy tanks wrong?

I started playing war thunder for about a month now. I am in the USSR tech tree. I didn’t want to research the heavy tank line at first since I had fun with the light tanks and medium tanks. But, around battle ratting 4-6 I saw so many players using heavy tanks like they were invulnerable. So, I thought I’d give them a try.
But, when I started playing heavy tanks, I seem to get killed more easily. When others use heavy tanks, whether its the Tigers, Churchills or in my case, the KV-1 and 2, I almost never seem to be able to destroy them, even medium tanks. I think I’ve never actually managed to destroy a VK-3002, my shots just bounce off it, and its not even a heavy tank.
I hate the slow reload rate and speed since I usually prefer faster gameplay, but I was willing to tolerate them because of the stronger guns and thicker armour. But, I still get killed easily even my medium and light tanks. I had some fun with the KV-2 which does seem quite invulnerable, but it simply didn’t suit my playstyle because its reload speed is way too slow. But, I expected the KV-1 variants to be better because when I see other players use them, they almost always get lots of kills and not get killed easily.

So, what am I doing wrong? Is there a specific way you should play heavy tanks that I’m missing? Are you supposed to carry a specific type of shell? I always carry APHE type shells since they seem to be the best.

It’s not your fault, like you said, the tanks may just not fit your playstyle. Warthunder is also a game that favors light or highly mobile tanks over heavier ones in general, and it can be a large transition to go from fast placed flanking gameplay to anything different. I would have to see your gameplay to give you any advice on what to do, I don’t play the KV-1, but I think it is a good brawler, so if you can try to engage in close range city fights, you may see better results? If yu decide to try this Mae sure you have some form of stereo sound, whether it’s headphones or an actual surround sound setup

Edit* as @EpicChicken22 said, it is important to only use heavy tanks at their correct BR. I typically avoid spawning a heavy tank if I get a full uptier as well because everything will be able to pen me easily

You are using heavy tanks at it worng br. Kv1 shiuld be at a br of 3.3- 4.0, and is 1, 2 at its br, is2 and is 1 can pen almist any tank head one