First question in AIBU so don't flame me too badly if I am BU 
A colleague of DH has invited us round for an evening dinner party. DH said he would have to check with me but didn't think it would be possible, we talked about it and decided that taking our 10wo baby was a really bad plan for a number of reasons. Mainly, his reflux is worst in the evenings so we normally spend hours cluster feeding/ mopping up vomit/ jiggling round the room. I can't remember an evening in our own house when we both sat down for a whole evening meal together for weeks. On Saturday we tried doing his evening routine earlier and going out, only for my boobs to leak horribly and we had to leave after the main course awful awful evening but there's a whole other thread about that Secondly, the only other guests we know for certain are invited made it very clear when I was pregnant that they can't cope with BF, so I'd blatantly spend most of the night hiding away in another room. Lastly, the last meal we went to at their house started at 7, with no sign of a starter until 9.30 and we didn't leave until after 1, right now I don't get enough sleep to cope with that.
So we left a voicemail saying that we didn't think DS or I could attend but DH could go by himself. This morning we get a text saying that they've been planning this meal for weeks, in honour of DS (despite only telling us about it at the weekend and it's this week) and they want to welcome him to their house and how if we can't go they will have to cancel etc etc.
I haven't been hiding away being a hermit since he was born, we've been to a wedding and a funeral (both 5 hours drive away), had umpteen overnight guests and am usually out and about. So, AIBU to think that if I say we can't do something because of our baby that should be accepted?