hey Lindsay,
as you know sleep here has been horrible since 18months but things are finally starting to get better! i think a lot of it was my denial that he needed his nap capped, tons of developmental stuff going on, and we got a groclock!!
anyways, i think if you want to push bt later you need to push the nap later also. liam is currently doing a 6.5-6hr45 A in the morning before his nap, then 1.5hr nap and 4hr 45-5hr A to bt.
considering that he is still doing 10.5-11hr nights, you don't HAVE to cap yet if you don't want to, but you do need to move the nap later i think if you want a chance at a later wake up. i think if you do that together with the gro clock and give it a week or two it will eventually work.
i don't know when you would like him up in the morning but this is what we have been doing
wu 645/7
nap 130-3
bt pd at 730, asleep 745/8
i started with the gro clock at 630 and slowly moved it later. i have a vid monitor so i see him when he wakes and he lies back down in the morning if the sun is not up yet. he has never fallen back asleep if he has already done 10.5-11hrs (if he has done less than 10hrs there is more of a chance of him falling back to sleep and then we have a good wu to work off of, yk?) but at least he is quiet and resting and that gives me a chance to wake up peacefully in bed with out rushing in to his screams, yk?
i think since you are still getting good nights with the 2 hr nap i wouldn't cap (unless you want an even longer night, of course) and do something like this, depending on when you would like wu to be:
wu 6/630 (bro clock on for 630 at the start and slowly move to 645, or so?)
nap 1-3
bt 730