I have had this cactus for about 5 (or more) years, and have been treating it pretty shamefully due to me only recently researching how to garden and unfortunately being one of those who didn't care too much before. I want to keep it alive, as it was originally a tiny cutting from one of my grandmothers cactus'.
She had potted it in a tiny pot with a lot of drainage stones at the bottom, which was perfect for the baby but I am aware it needs repotting now. Water doesn't seem to stay in the soil at all now, just drains straight through. Was planning to put into a pot 2-3x the size with fresh potting soil (I assume it can handle the same soil as my herbs do?). That's easy enough. I'll keep it inside at a window as that's where it's been it's whole life.
The problem is that i'm worried that this white fluff that i've always dismissed as part of the plant is mealy bugs. In the above picture you can also see white discolouring around the middle of the plant. I don't know what kind of cactus I have, unfortunately, but my grandmothers ballooned out into a ball shape and mine never has even after 5 years. I've put this down to mistreatment (it was left on a kitchen shelf in my parents house for 3 years with sporadic watering) but apparently mealy bugs cause stunted growth too. It keeps growing up, not out. Is it just because it was originally an offcut 'stem' so it's never going to become a ball? If it is mealy bugs, is this a huge infestation that is going to be really difficult to deal with?
Thank you for any advice! If anybody might know what kind of cactus this is so that I can research online for how to look after them, that would be really great too. :)