1 hr pm nap (which is the cat nap), correct?
That was nap 2. A CN is a shorter nap of 30-45 mins.
Or was there a 3rd 1 hr nap as a cat nap on days your child wouldnt do 2 long naps and her A time is already 2 hr 45min+ ?
For a while, I would do a CN on days when naps were short but after a while, I actively worked on lengthening naps by being in her room at the 30 minute mark and patting her back to sleep if required. I had to stay in the room patting/resting my hand on her for the rest of the nap for 2 weeks (I think). Then I backed off completely and she slept through. Such a relief. Otherwise, if the naps ended too early, I went for an EBT.
How long of a gap should there be from the second nap to bedtime if little one has a short second nap of 1 hr? 2.5hrs or 3 hrs A time? 3 hrs seem long if sge only had 1 hr nap, isn't it?
This depends on your LO. How long a gap does she need to bed? My DD always did her shortest A to bed. We had looong A times through the day but she could wake up from a 2 hour nap at 5 and still would be in bed asleep at 7pm sharp and STTN. She could handle a max of 2.5 hours to bed at that time. It was very easy to tell when I had got a timing wrong because BT was always easy and she always SS (until she didn't. But that's another story) A 1 hour nap isn't really a short nap. 30/45 mins is.
WRT to the routine you posted, try for 6 pm and see what happens. Or try lengthening that nap. I capped to 1 hour because it was too close to bed but you need a bit longer nap to sustain this.