Hi Loula! Welcome!
Ok- it looks like the issue you are having at the moment is that she is needing a little more awake time. Basically she has started sleeping less as she isn't tired enough to sleep longer than that. Then it turns into a cycle- in that she then can't stay awake longer than an hour as she's only slept for 45 minutes or so!!
What you should look at doing is gently push up her A time- even by 10-15 minutes (or 5 minutes!!) every couple of days. It can be ANYTHING- a walk around the house, look at the garden, a trip to the letter box was one of my favourites! (walking SLOWLY!). Just as long as she's awake! The Awake time includes everything until she has her eyes closed to sleep.
Here;s some links to give you an idea:
http://babywhispererforums.com/index.php?topic=128419.0http://babywhispererforums.com/index.php?topic=64158.0Now- i can tell already that you are saying 'no- but she couldn't possibly stay awake any longer?!?' and ' BUT you say to follow the tired signs' ... Basically babies get used to being up for a certain amount of time, and shw waht appears to be tired signs after that time. I often will say 'mummy knows best'! My guy HATED the first A time push- HATED it!! But after that it was a little easier.
You;ll probably find that every 6 weeks or so you'll need to stretch the A time n this way.
Also- when i was trying to extend naps i would have a set time- say 15 mins or so that i'd try and then give up, get him up and feed him, starting a ne cycle. You will probably not have much luck resettling after an undertired, or 45 minute nap. (I think in 4 months of trying i managed to extend 2!)
The other thing that some people do while trying to get this to all work is that you can go EASASE instead of the usual EASEAS..
Let me know how you go!