Have Cat Questions? Ask a Cat Vet Online.
It sounds like you might be feeling mammary tumors or fatty tumors on her belly. You should see the vet to find out which one you are dealing with. The vet will do a needle aspiration and put the contents on a slide and can tell you right there in the office what you are dealing with.
Fatty tumors usually come with age and are harmless.
Let me know if you still have questions.