My LO is 9.5 months and we're only now starting to have some consistent success with naps (in the past week!). The key for us was ignoring lots of yawns and eye rubbing and putting her down when she seems really, really tired and didn't even had energy for play. Really. Now we have 3-3.75 hours of A time and she naps 1:15x2. This never used to happen. Maybe I'd get one 1 1/2 hr. nap a week! The rest were 45 (or 35).
I think the window of opportunity opened around 7 months (but I didn't seize it until now). That's when what I thought was enough A time only yeilded 45 minutes.
I should note, however, that this turn around in naps started the week I decided that I wasn't going to just get her out of bed but try to extend them. The extension only worked a couple of times, when she woke after 35 mins. It never worked (or has worked any time I've tried) after 45 minutes. For me, the success with 35 mins. gave me the courage to try to drastically extend her A time, figuring I'd rather get 35 and extend than 45. And if the 35 mins. didn't extend, I figured, what's the big difference in 10 mins. So, I took the plunge and lengthen her A time from 2 or 2 /12 to 3 1/2 and voila!
Take heart. PU/PD isn't the only solution. Do enjoy yourself and motherhood more. But don't resign yourself, if you know your LO needs more sleep. In time, you'll figure it out.
(And please know that I am totally struggling with other sleep issues, NWs and EWs. Thankfully, I'm getting some relief with naps.)