An occasional hairball is tolerable - say your cat has a couple a year. Multiple ones, weekly, is not. There are serious complications that can arise from them.
There are a few things you can do to help:
Get a deshedding tool such as a furminator. This is not a brush or a comb, so saying you "brush" her occasionally isn't the same thing.
Get some hairball remedy. You could start with Laxatone and discuss some other brands/formulas with the vet. Make sure she gets this daily for a while, a couple hours before eating.
Diet. Poorer quality foods low in omega fatty acids are often not good enough for many cats skin and coats. Occasionally even a higher end food is not the right match for a particular cat. At the very least, supplementing with a high quality fish oil supplement can help.
Having enough fiber in the diet will also help a cat pass the fur before it can build up in the belly.
Mollie does need a vet visit for this, though. You can't skip it. Tell the vet your concerns and discuss diet options. Some cats even have to go with a prescription hairball formula if their hairball problem is severe enough.
Have some blood work done on Mollie, too. Health issues, like hyperthyroidism, can cause poor coat quality and shedding as a symptom.
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