Hi Adrias' First,
I hate to do this to you, but I think you may need to shorten the morning nap time a bit
. I know, am I crazy or what?
I just know that with Taylor if I let her sleep too long in the morning then she will ALWAYS without fail take a short pm nap which is a nightmare because she is super cranky all the way to bedtime. I would first try to cut the nap to 1.5 hours and see if the afternoon nap lengthens at all. Try this for a few days to see if it works before you then try to even go for 1 hour 15 minutes.
I know some may not agree with this, but I have jsut come to terms that not all babies (mine beign one of them!) will not take 2 glorious 1.5-2 hour naps a day at this age, and so I would rather have a longer pm nap than a am nap.
That is just my 2 cents though!
Please let us know what you decide!