Hey eebeejeebee,
You can try and increase DD's A time to around 3:15, then 3:30 etc.. I did this with my Dd2 by adding 15-20 mins to her 1st AT as I knew she could handle it. Her subsequent ATs during the day were shorter but I tried to push each AT out a bit (e.g. 5-10mins). If she ever woke up at 30mins into her nap, it meant she was OT, and I shh/pat her back to sleep. Sometimes, I ended up APOP with her sleeping on me just so she could rest/sleep until the next cycle began and to keep her on track. It took a few days but eventually she got used to longer ATs. And you will end up with not enough time to fit a catnap in due to the longer ATs.
BW says to extend ATs slowly at 10/15 minutes every couple of days to allow your LO to get used to the increase in A time- otherwise they get OT. Maybe start with this and see how your DD takes it?
HTH,
V.