By no means am I an expert, but I've brewed a barleywine every summer since my son was born (so 3 times now) and here's what I've done / found out. I can post the recipe too if you'd like
If you can, play around a little with your water chemistry. I did on the latest batch and already I think it's better than the other 2 and it's only a few months in the bottle.
I added 2 types of crystal and special b malts for a little more complexity. 3 might be too much, but I think you can easily do 2
I'd also push the abv up to the double digits and adjust the hops accordingly and maybe yeast if it cant handle the higher alcohol. You're making a barleywine dern it, not just a strong ipa.
Is there a particular reason you're using american hops vs English ones? I usually dont adhere strictly to style guidelines, so I'm just curious.
Hopefully some of this rambling will be helpful to you