How much 'awake' time ~ 5-6 months old?

Miss L is 5.5 months old and at the moment she struggles to stay awake for more than an hour during the day before needing a nap. Don't get me wrong, I am *thrilled* that she sleeps during the day as when she was younger she would only have around 3 x 30 min naps during the day. Now she will do around 3-4 sleeps of between 1-2 hours.

But in between naps, she gets tired (and subsequently grumpy) fairly quickly. This is fine if we're at home but makes it hard if we need/want to go out. By the time she's fed and changed and we're out the door, we're lucky to get somewhere and have 30 mins before she needs a sleep, and she's not good at sleeping in her pram. Actually let me rephrase that - she won't sleep in her pram unless she cries herself to sleep which I am not going to do in public (we have taught her self-settling so at home she may cry for a couple of mins then fall asleep, but usually she goes to sleep without crying at all). So people are starting to think my gorgeous little girl is 'moody' and 'grumpy' - grrrrr (I hate it when people make comments like that - hello, she's a baby and she's tired!!!).

Just wondering if this is common for around this age? It's been happening for about the last month.