Well, I can't say 2-1 transition really applies here. If it did, then PM nap should be going gangbusters due to that short AM nap. But it's not.
You've got a wonky situation b/c she's acting tired all morning. She's STTN, right? If she wasn't acting tired I'd say that she needs her A time to extend in the AM and that her nap is UT. But acting tired makes me wonder if she's OT for that AM nap. Walking can definitely tire a LO out! Esp. one who starts walking as young as yours did! Is there any sign of molars by the way?
As crazy as this sounds, I might try a 9:30 AM nap and see what happens. Alternatively, have you ever tried pushing nap to 10:30 or is that just impossible with her being super tired by that time?
There's also a long A time after AM nap, which would make me feel like nap#2 is def. OT. I'd move Nap #2 closer to #1 esp. since she's short-napping in the AM. During the 2-1 switch we generally advise putting 3 hours of A time between the 2 naps, and you've got, gosh, 4-4.5? that's REALLY long for her age with only 30 min of nap under her belt.
So, try this:
9:30 nap #1 (let's assume still only 30 min)
10:00 awake
1:00 nap #2 (no later than 1:30) and hopefully this will be 1.5 hours
2:30 wake
bed 6:30
Now, if you think a 9:30 is crazy and that it's more likely that scenario #2 works (where she's UT for nap#1 and needs to extend) then I'd do:
10:30 nap (we'll assume 30 min)
11:00 awake
2 pm nap (hope for 1.5 hours)
3:30 awake
7:30 bed since that seems to work for you with that awake time.
I have to say that for her AGE, scenario #2 makes sense. Especially if you've had her on the same routine for more than a month. I might try that 10:30 nap time first and see what happens. But molars and teeth can really wear a kid out, so I'm not ruling out the needing an earlier nap scenario!
Guess final answer: use your judgement as to which routine change to try first. Leave her at that routine for 3 days and then we can examine her behavior and make changes based on what you've observed.