I know how you feel, this transition left me feeling like an absolute failure as a mother
I wasn't but it just totally through my confidence as too wether I had a clue what I was doing. I think your doing great, her NW's seemed to off stopped her wake up time is getting better so huge progress really
Is she caught up yet on sleep do you think? She certainly seems to be improving with no NW's and her nights getting a bit longer again. As you said following a good nights sleep and a 6am wake up she then only took a 30min am nap, probably wasn't tired enough to sleep longer, rather than OT JMO.
I think possibly you need to decide what works best for her, a long am nap and short pm nap or vise versa. I don't think at this point you are going to get 2 long naps again, we know she was transitioning from the start.
So when you think she is caught up, even if her day starts at 6am and ends at 6/6.30pm then you will need to make a new plan and stick with it, just like you are doing now. Unfortunately no one can advise you the right route to go, thats your descision. Even if you choose the wrong way you can always re think and do the opposite as long as you give things time to have effect and act sooner rather than later when you see its not working.
I totally cocked things up with Lily, I went the short am nap long pm nap route, unfortunately Lily would always do a short pm nap if the am nap was short and I battled with this for ages until I just went cold turkey onto 1 nap as 2 just weren't working. If I had acted sooner and left am nap long and tried for a late catnap or been brave enough to try for a super early bedtime things would of gone a lot smoother for us I think.