Work on two areas when you putt. 20-40 foot putts, getting those within a 3 foot circle and then work on 6 feet and in. Become great in short putts and long putts.
Don’t worry so much about the 10-20 footers they will be fine. The key to not 3 putting is distance control with your long putts… solid contact, good tempo and a long enough back stroke. Then focus your practice on 6 feet and in from all angles of the hole.
Also mentally treat all outta the same don’t out more pressure on those short ones and be loose on the long ones. Have a consistent routine and you will make many and miss some but it will all even out.
Lastly believe you are a great putter!!