Help!

This is my 2nd year with vegetable gardening/sqf gardening. Last year, I set up two 4x6 9" high beds. When I did the Mel's mix last year, I was in a hurry and did not do all the research, and just used leafgro (humus compost with grass clippings and leaf, which does not have much nutrients) for my 1/3 compost part. My garden did fine, for my first year. Zucchini and all my leafy veggies did great, tomatoes and carrots were decent too, but I have no other years to compare to :)

I want to see if I can "fix" my mistake before I plant things this weekend! I do not have homemade compost (starting this year) but I have a local garden center that carries l different types: cow manure, chicken manure, mushroom, lobster, earthworm castings, etc.

How should I go about this? Do I just mix in a few different types of high nutrient compost before I start this year? Or would it still have to much of humus compost, and I need to think about scooping some out and replacing it? I am adding about 12 cft of garden space this year, which is not prepared yet, so I could scoop the existing mix in the boxes in the new box and add new/more balanced compost in all boxes?

What types of composts should I look to add in the existing boxes to achieve more balance/variety of nutrients?

What would you do?