it is possible the vomitting is behavioural, but i'd rules out medical issues first. It could be an organ problem, she's a bit on the young side, but getting close, so quite possible; my first cat got serious kidney problems at 9 yrs. I'd talk to the vet, explain the symptoms and concerns. To test for major medical problems, they'd take a blood sample, and they can put her out for that. many such problems can then be treated dietarily, but by the symptom of vomittign alone you don't know if its cause A, B or C and each has a different treatment whcih could be bad for the other.

Another thought- anythign new int he house/enviroment? A new plant she might be nibbling the leaves off of? A new carpet cleaner that was used etc..? Things that we wouldn't think about ingesting but she might be eating/licking.