Looking at the screenshots you provided, lowering the game Q appears to have freed up enough RAM, about 2GB. 82% utilized is still on the high side but way better than 90%. There still may be some periods of thrashing so keep an eye it, close apps that aren't needed.
Yes! I've tested 1080p 6000bitrate and it worked! (120hz)
At least on the statistics of OBS, also task manager seems like above.
(Fore the log ignore the audio monitoring problem, I've just disconnected the headphones)
I've also close some "client" and "help" of the photoshop program.
Never had RAM problem until now, I'll keep an eye on it.
Relatively soon I'll upgrade my PC.
I will run another little test tomorrow morning and if there's no problem I'll finally start again to stream.
For now thank you very much for the support. I know I'm not an expert in certain things and that it's not very easy to communicate with those who aren't.