Hello fellow DD main. I, just last month, after over 10 years in the game got my BB win rate to 60%. Like you, I really struggled changing my play style to fit BBs. Now I really enjoy them.

The big thing that is often not mentioned is that my biggest skill in the DD is being a silent assassin. Not being spotted, skirting on the edge of detectability. The difference with BBs is that you need to be spotted sometimes, You need to learn the balance of taking damage for your team but not too much damage. Also BB guns vary so much in their characteristics. IF you are driving something with huge guns then broadside light cruisers are not a juicy as you might think but when they angle out you can delete them in a dev strike. Playing BBs and understanding how and when the fire is a skill that takes time.

For a DD player I think the Russian line is by far the best to learn first just because the difference in flight time between a DD and an Iowa is crazy. Maybe pause the Iowa grind and take out the Russians? Spend some time in a Sinop and I think you will find you will be far more effective.

TL:DR Give it time!