Hi Hun,
((HUGS)) short naps are super stressful! On the whole her amount of sleep on a good nap day, which correct me if I'm wrong is around 14 hours

should be fine. But tell me in the past has she been high/average or low sleep needs

Obviously there is a big difference for a LO between a 10.5 and 11.5 hour night, so have you noticed if the naps are shorter on the days following the shorter night

I'm wondering if they are OT nap WU's and now she has accumulated OT

A 5 hour A time is good upon switching to one nap, so that shouldn't usually be a problem, but maybe if she has had a shorter night you could bring the nap forward a touch to see if she naps better. It might also be an idea to always wake her at 7 to try and achieve better consistency at the start of the day, although I know the temptation is to allow a little extra after a later night, it does tend to work out better.
Are you trying to achieve a 12.5 hour day

If she is high or average sleep needs you could also try bringing BT forward and make her day 12 hours, even if it's just an interim solution, it may help her naps to lengthen.
Also I'm presuming there's no current signs of teething

although I would expect nights to be as if not more affected it there was anyway.
Let me know your thoughts.
Vicki.x.