No, its not that simple. xx
She does have crazy-high A times for her age, but you really don't want to be on one nap at this young age - too many things can go too wrong.
If she's like my DS, yes, it could be something as seemingly ridiculous as the cot change. What they see when lying down in the cot is very different - the bars look like they stretch a really long way up compared with before. Its not the familiar place we think it is, yk? Their safety zone has changed.
Is OS maybe playing into it a bit? Just something for you to think about: what's the emotional atmosphere like at your place at the moment? I just wonder if its higher at the moment and she may be picking up on it.
What about
7 - up
11 - nap
1 - wake
4:30 - nap
5 - wake
7:30 - bed
That still leaves you with a better-length day and another chance if she doesn't nap well after 4hr. Its something that usually happens around 9-11 months (it varies) as the 2-1 nap transition begins, but if you do need to increase her A time from 3hr30 you're not going to be able to fit two long naps in without making the day too long.