Struggling with Apple Tree — would appreciate advice

I want to be honest: I'm not getting great results with Apple Tree and I'm not entirely sure why. late frost damage to blossom in exposed positions has been a recurring problem despite my attempts to address it. I've been focusing on thinning fruitlets in early summer to improve individual fruit size based on everything I've read.

dual ornamental and productive value in a garden is there in glimpses, which tells me the plant has potential in my conditions. I have it in a large half-barrel container on a sunny patio which might not be ideal. winter pruning while the tree is dormant showed some improvement. Two stars for now — not the plant's fault, but not a success yet. I'll update if things improve.