Oh Hon please don't be so stressed. Really no matter what you do there will be much more crappy days and crappy naps. Couple of crappy naps transitions in front of you:).
APOP means accidental parenting on purpose. When you are doing sleep training it's not the best option to do it, but for a sleep trained kid occasionally just to catch up and keep OT at bay, it's really useful. Used only once on couple of days, it won't harm and it will help you to keep your sanity.
You need to extend A times honey as this seems to be the biggest problem I guess and is resulting in short napping. I would consider two options. Either push all A times and aim for 2 longer naps. Or keep first nap as it is and push second A or keep it like it is today so your second nap will be the longest one. In terms of routine at 6mo you could go for:
1/ 7am eu
9:30 nap for 30min - wake at 10 if needed
12:00/12:30 nap for 2h
4/4:45 short nap for 15-20min
7bt
2/ 7am wake up
10:00 am nap for around 1:30
14:30 pm nap for 1:30
7pm BT.