at HVs! If you want to feed during the night at 7 months by all means do it. Fair enough your DD may not 'need' it for survival, but a lot of babies still prefer it!
IME, babies going through development spurts start wakening when they've previously been half decent sleepers.
Weight gain slows a lot at this age as they start to get active. My DS was 20lbs at 9 months (only weight I can remember lol) and took another 6 months to gain anothe pound!
I've done CC with DD (now 10 months) as I have been at my wits end with her sleeping on several occasions. She's wakes a dozen times a night or more and won't settle without me. I had no success - just a lot of tears for hours! I do feel horribly guilty as I don't believe in letting them cry as I worry about the stress hormones. Having said that I'm now doing controlled comforting (I stay with a hand in the cot the whole time!) with her as we've hit a total brick wall on getting her to sleep, and over the last few nights we've had a teeny teeny bit of success. We tried it last month and got nowhere. So I do think age is a factor. 7 months is when the clingy thing starts happening too - along with teething!
I do worry that DD has so little sleep, but I worry from her happiness and growth (height) developement (she's very short!) more than anything. Her other development is pretty fast - she was rolling at 11 wks, commando crawling at 5/6 months, proper crawling at 7/8 months and pulling up and cruising before 9 months. She also has quite a few words and is generally happy an sociable. I've been told that 'wakeful' babies learn faster as the more time they're awake, the more time they have to learn!
Do what comes naturally to you. And if at any point it's not working for you, then fix it. I also agree with piffle (I think it was?) about missing the cuddling/waking/breastfeeding. DD is my last and the baby parts are gone so fast it's worth holding onto!