It is very hard to answer questions about shedding in cats as it is very variable in the different breeds.
Some cats will shed fur more or less continuously over the year and other cats will shed mostly in the spring and autumn.
When you brush your cat during shedding the amount of fur you get off from your cat can be amazing (it looks like you will have enough fur for a spare cat in about a week).
If your cat gets hairless spots or is itchy, you need to consult your vet to get it diagnosed and treated.
You should mention the hairloss to your vet at the next consultation; as it is now I do not think you need to worry about your cat's health.
Here is an article on catcareofvinings.com about the difference between normal and pathological shedding.
Some information about the skin and fur of cats and dogs is also in this PDF file.