I don't think I'd consider 6 months 'fully weaned' either even if she is taking 3 meals a day. They go through a growth spurt at around that age as well, so she may just need the milk that she's waking for at night.
Depending on what kind of solids you're giving her, she may just not be getting enough calories or nutrients from them. Purees and rice etc. tend to not have a lot of calories when all is said and done.
You could try either increasing her milk during the day, or giving her more calorie dense/nutrient rich foods during meal times as long as it doesn't affect her milk intake too much.
It may just be that because she's going through a growth spurt she's wanting a lot more than normal and that given a week or two it'll sort itself out.
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