I get it:
You're doing it right by going through the missions. It is repetitive actions that become muscle sensory after many 100's of times used over and over again.
You're trying to learn what only a select few were ever able to accomplish in their military career. So, what to do about it?
1. Use settings that make you invulnerable until you get it.
2. Use settings that give you unlimited weapons and ammo and use it "non-sparingly" is that even a word? ....
3. Move to another aircraft, learn it so-so, this will open other parts of your brain to rewire motor skills to situations.
4. After practicing the missions, a hundred times, take the invul off. Set a goal, if you die, no DCS for 2 days then move to the next mission live.
5. Get a buddy to fly with you, can't stress this enough. Two men working together to accomplish the same goal is called --bonding.
6. Fly with your bonded friends in multiplayer missions, see where you are compared to others.
7. Now go back and practice again until you can literally know what the trainer message is before he says it.
8. Make videos of your flying and promote yourself. Gain confidence and be a leader for others that were in Your Place just two months ago.
9. Buy a campaign and do it front to back, show the developer what you learned and give him thanks for his time creating something for YOU.
10. Don't whine in public that it is hard. We know it's hard and it will get much harder the more serious one becomes at trying to succeed in this unique "game"
Poppa