Is it just me or is USSR 10.3 just suck to play?

As a free-play, this week I finally got the T72b, and oh boy, it sucks butt to play in this rank, I heard a lot of people say that 10.3 USSR is good or something, but like 8/10 match will be full-up tier, my least favourite to fight is the FUJI tank, I rather fight an Abram than that, it has good reload speed, speedy tank. I feel like they have better traverse and other mechanics that make them faster to shoot at my weak spot, it makes my T72 B look like it was made in the Cold War. Open map is a pain as most tanks I fight have thermals.

As I played the game, I got the T72b 1989, for its armour, while it helps, it doesn't do much because the tank I fought keeps shooting at my weak spot. Now because I'm new to 10.3 maybe it's just that it's a skill issue as I see this BR is more into speed and traverse speed, how fast can you aim and position and all that stuff.

The question is, should I just get the t90a, leaving 10.3 to 11.3/11.7 or do I get the T80b and stick to 10.3 will most match fully up tier? after playing this game for 540 hours, I wanna buy my first ever premium, now a member of the snail. I was thinking of going all the way to 11.7 to get the t72B3 and buying the t80UE1, maybe a jet or k50, or should I just buy the 10.3? vehicle like t72 turm, 2s38 or other?