Ok, this will be my last post, then I won't be checking this thread again.
I can see now that it was stupid of me to post this in AIBU.
If you have a child that can be flexible about their naps, and can cope with a missed nap, then all I can say is, you're lucky. Please appreciate that not all babies are like this. My dd really doesn't cope well with a late or missed nap, and is liable to have a meltdown, then be cranky for the rest of the day. This is why I wanted to change the appointment time. I have no idea what goes on at HV reviews, as this is my first child, but I'm guessing it's difficult to assess a babies' development if they're screaming.
If you've only ever had good experiences with HVs then you're also lucky. Please tell me where you live so I can move there.
Unfortunately I don't go out to lunch with friends/shopping/to the library when DD should be napping (as somebody asked), as I find it's not worth the stress that a missed nap results in. She won't sleep in the car or the pushchair.
I seem to be getting some barbs for crying. I didn't mention this in the OP, as I didn't feel it was relevant, but I have been suffering with PND since DD was born. I realise now that it was totally stupid of me to post something like this on mumsnet when I'm feeling fragile and vulnerable. I know I brought it on myself to a certain degree by posting in AIBU (I didn't know there was a chat), but I'm still saddened that some people feel it's ok to judge and criticise other mothers. We should be supporting each other on here, as at the end of the day, we're all just trying to get by as best we know how. I know I asked for opinions, but I do feel that some people have been unnecessarily unpleasant.
To those of you who have been nice, thanks for the understanding and support.