Molly - IMHO ... the first 10 weeks of having a baby isn't the easiest time. I'm really worried about you having the extra pressure of trying to get into the right shape to fit into your dress. Also, is the style good for feeding? I've thought long and hard about saying anything but I've decided it's better to say it now than wait until your baby is here and it's too late - then I'll just kick myself.
Of course, I could be worrying unnecessarily. Like you say, your family know you and your body and have all been there. So they're probably the people you should be listening to.
Ellie - I got a Maclaren Quest when DD1 was 6 months old. I got it specifically for travelling and have never looked back. In fact, our extremely expensive buggy has hardly been used since we got the stroller. It's so light and easy to fold and DD1 loves it so we've used it as our main buggy since we got it.