I need some help by people that like realistic shooters.

I can't say a lot of RO2, but the few time I played It was very addictive. I recommend RO Ostfront 41-45. There's a Russian server that has around 30-50 people on weekends. Maybe daily I'm not sure. And "Darkest Hour" mod seems to be popular.

I saw Insurgency and I didn't like the same style as in CS-GO. Weapon mechanics might be real but you still have the small maps like Valve's game.

maybe you should check "squad". only heard the best

You should check out day of infamy by the guys who made insurgency, Haven't played it in a while but it was a lot of fun. http://store.steampowered.com/app/447820/Day_of_Infamy/

Keep an eye out for Escape from Tarkov. Super realistic from what I have seen in youtube videos.

ArmA?

As someone who played both (56 hours in Insurgency, 420 hours in RO2/RS), I would definitely recommend RO2/RS.

Insurgency is a fine shooter, but there's a point when it becomes boring and you stop returning to it. RO2/RS is extremely realistic and addictive. After you invest several hours and the game stops being about the single question "How the hell can you tell who is on your side and who is the enemy?", the overall experience becomes very involved and gripping. The sounds, the music, everything blends together to create something that feels like a real battle. There are some epic maps, especially in the RO2 part of the game, but most normal-sized maps are fun too because the immersion effect grabs you from the very first minutes. Some reviewers talk about the game giving them PTSD and I can see how it can be true (the most horrible thing in the game is probably to be burned alive by a flamethrower).

However, aside from disturbing memories, the game can also give you a riveting experience of fighting until the last drop of blood, desperately holding under heavy MG fire with your comrades shouting in anguish and dying all around you, and then returning to the real life and feeling relieved and grateful that the war is over but also determined to do anything you can to stop another war like that from becoming a reality.

TL;DR: Insurgency feels like a fine game. RO2/RS feels like a war.

Red Orchestra 2 was pretty bad...
Though I only really played through the singleplayer campaigns.

Tom Clancy Wildlands, play in Extreme mode as the AI is realistic enough. If you finish the storyline, you may progress with Tier and weekly challenge rewards. Also if you love pvp, there's a Ghost war 4vs4 too.