@1
"have bigger opening repertoire or stick to one" ++Stick to one to accumulate experience.
"As white I stick only to Queens Gambit" ++ Good.
"As black I reply on d5 with principles of QGD" ++ Good.
"For e4 I like caro-kann" ++ Good.
"if I should stick and improve by playing what I already know" ++ Yes.
"try to play a lot of variations and openings to gain more experience?" ++ No.
I think you are on the right track. Although, I have noticed that you struggle against 1.d4 Sidelines. I suggest you check out this study so you can have a better understanding of how to beat them. I know you don't like to focus on theory but this will give you a better understanding of the opening and the middlegame that arises especially the London
Thanks for the tips, and it is really strange that my best part of the game is opening where I am in most cases in better position but I never learned any opening at all 
When games are wild and open I make a lot of blunders...I am weak at tactics and try to get the best out of good positions. That's why I am not aggressive.
If players do not play d5 I usually continue same way like they did and mostly focus on C file and queenside.
It really doesn't matter in my opinion. The QGD is as good as any other classical opening. So I would stick to it (at least for a while) until you get bored by it.
Hello,
As you can see I have rating of around 1500 so I am somehow post beginner - intermediate player. I would like to get opinions if it is good in this stage to have bigger opening repertoire or stick to one.
I of course do not study openings in this stage, I just learn them randomly from instructive games so I do not know intense theory but only principles and like couple of moves.
As white I stick only to Queens Gambit (learned that pretty good from Chernevs book Logical Chess). I recently discovered English Opening (couple of games from book The Art of Logical Thinking) but I just can't use to it and get a lot of messy positions.
As black I reply on d5 with principles of QGD which I know as white so I know how to play as black too. For e4 I like caro-kann and play 90% of time that and recently from book The Art of Logical Thinking I learned basics of sicilian defence.
So my question here, for improving purpose, is if I should stick and improve by playing what I already know decently or to try to play a lot of variations and openings to gain more experience?
I must mention that I do not have opponents which who I play often so no need to have variety of weapons.
The QGD and CK are solid choices! If I was your friend, I would say continue with those.
Do not entertain the Sicilian and English; I can say that because I play those two exclusively with the odd Reti for transpositions.
I do my opening study on Chessable. It's more work than I ever would have imagined. I'm getting better at it now and progressing much quicker, but it was not easy. If I knew what I know now at the time I started, it could have been much easier.
Learning lines is nowhere near as important as learning ideas. It sounds like that's what you've done with books is learn ideas. Every opening has basic plans and as long as you know those you can pretty much play through any variation. I would say to study courses with very few variations, but read as much detail about the ideas/plans as you can. Each course has all that explanation. Stick with the absolute most basic courses though. They will still be a tremendous amount of work.
Hello,
As you can see I have rating of around 1500 so I am somehow post beginner - intermediate player. I would like to get opinions if it is good in this stage to have bigger opening repertoire or stick to one.
I of course do not study openings in this stage, I just learn them randomly from instructive games so I do not know intense theory but only principles and like couple of moves.
As white I stick only to Queens Gambit (learned that pretty good from Chernevs book Logical Chess). I recently discovered English Opening (couple of games from book The Art of Logical Thinking) but I just can't use to it and get a lot of messy positions.
As black I reply on d5 with principles of QGD which I know as white so I know how to play as black too. For e4 I like caro-kann and play 90% of time that and recently from book The Art of Logical Thinking I learned basics of sicilian defence.
So my question here, for improving purpose, is if I should stick and improve by playing what I already know decently or to try to play a lot of variations and openings to gain more experience?
I must mention that I do not have opponents which who I play often so no need to have variety of weapons.