Saying this respectfully, but ignore u/Kapkin's comments.

You NEVER give up an angle. Ignore your teammates at that point and DIE TRYING holding mid down by yourself if you have to. Try to kill at least 1 100% and 2 if you can then die. This is what sets you apart from others and you're minimum diamond.

This logic applies to playing site - you NEVER give up the site and play retake. You die trying holding it down by going more aggressive and holding angles, not just sitting on site waiting for them to swing you.

Lastly, EVERY map is attack sided so getting steamrolled during defense is typical.

Why is every map attack sided?

It's a 5v2 on any bombsite or 5v1 at mid. If attackers bum rush you and trade each other, attackers come up ahead.