Sounds like your supply might have regulated. Did you have oversupply in the beginning? It's normal for it to regulate later (Around now) if so. Otherwise it tends to happen around 3-4 months. The other signs of this are that your boobs used to feel heavy and full between feeds, but now they feel soft and floppy all of the time. Does that sound like what's happened? If so don't worry, it doesn't mean you're not making enough, it just means you're no longer making too much. It's regulated to what she needs.
If it's not that, it's possible she's reduced her demand a bit due to solids. Keep feeding her as usual and it should come back up to as much as she needs. Don't panic; at eight months she'll be able to make up any shortfall with food. But keep an eye on her nappies over the next couple of days, count the number of wet ones. Being dryer overnight might mean absolutely nothing on its own - as a pattern of generally producing less, then it would be something to take note of.
Could she be coming down with something? It might be that if she's not feeling well, she's not been stimulating your letdown reflex as she normally would - she might be gearing up to drop the bedtime/night feeds, it might have been a total one off, she might have a new tooth coming through which is affecting her latch (which will be temporary).
Other than that, I can't remember now, so perhaps someone else can advise, but I wonder if it's just a part of breastfeeding an older baby, that the letdown doesn't feel quite so strong any more. Certainly, I remember feeling more of a "gush" in the early days/months of breastfeeding which wasn't there any more when DS was older, he'd feed and get milk but if he came off it wouldn't squirt around, I couldn't express much by 8 months and never managed to express more than a drop after that (though I breastfed for four years, and he didn't eat much in the way of solids until he was nearly two yet he was growing, so there was definitely milk there).
Does she seem distressed at the lack of milk, is she coming off sooner than normal? I wonder if she's getting it but the method of delivery has changed slightly. Have you started your periods yet? It could be that you're about to. Any chance you might be pregnant, too? I don't think that would affect it early on, but any hormonal change could have a possibility to suddenly change things.