Thank you all for the sympathy and suggestions. It lovely to have your support 
I am feeling a bit better after a lovely nap but am also a bit pissed off because I left DS with DH and PILs, trusting DH to make sure DS went down for a nap when he needed one, but instead DH had a long nap himself
He left DS with PILs who let DS stay awake for 3.5 hours since his last nap... DH then brought DS to me for a feed and he obviously fell asleep at the boob (which I have been trying to avoid) a whole hour late, which is now going to interfere with bedtime. How am I supposed to relax if I can't trust DH and others to look after DS properly 
purple
Sorry you had a bad night, must have been difficult to muster the energy for the wedding. How did it go?
The website I rate has an article about long night wakings, here's the link in case it's helpful: www.babysleepscience.com/single-post/2014/09/09/The-“Split”-Night-Why-some-babies-are-awake-for-hours-in-the-middle-of-the-night-and-how-to-change-it
troodie
I've read a few websites and books and I really like Baby Sleep Science because it seems very balanced and sensible. It's one of the few things I read that seems genuinely in the middle in terms of "gentle / attachment parenting" v strict sleep training, and they give options to choose from rather than a "one size fits all" approach. There is a resource blog with free articles and also a nap guide which is $10 to download but I found it helpful.
I also like "The No Cry Sleep Solution" by Elizabeth Pantley which I think is particularly useful if you are breastfeeding and/or cosleeping, but also has advice for bottle fed babies and sleeping in own cot/room.
Mother
Happy half birthday to your little one! My DS is 6 months old today as well
I took some photos with the 6 month milestone card we have and he was mostly interested in trying to chew it 