What you've got is about the best you can do with just supermarket juice and no extras. The flavour tends to be a bit thin as it's designed for drinking rather than brewing. Hunt around for the best tasting juice you can find next time. Also you don't mention tannin - turbocider definitely needs it, and this may be the real shortcoming of what you've made.
Mostly people use (per gallon) a mug of very strong tea for its tannin and a bit of flavour, and use half a litre of something other than AJ to round the flavour out.
And time in the bottle helps too.
To rescue this lot, maybe mix with a little fresh AJ when serving, to get some of that apple back. Maybe even try serving it over some teapot leftovers! But at least leave it a month to let it mature a bit.
If you want to really get more apple in it, you might consider using actual concentrate at some point in the future.
500ml of the Suma stuff is equivalent to 3.5l of AJ, which given the tea and the some-other-juice, is how much you use in the basic recipe for a gallon. But obviously you now have 3l of spare space in your demijohn, so you can put more AJ in it. Unfortunately this also ups the ABV so you have to stop before it gets silly.
I've had good results with 500ml Suma, 1/2l other-juice, 1/2l tea, and 1/2 or 1 l AJ.
Later this year I may try just going with 600ml Suma, the other stuff, but no extra AJ
When you get something you're beginning to be happy with (you will), start thinking about going for a malolactic secondary fermentation
Oh, and: what yeast did you use?
