The things I spend most on are clothes, food, and guitars/amps. It's all proportional, if someone earning 50k a year were to buy a Belstaff jacket and a new pair of Loakes once a month I would consider that perfectly normal because I buy roughly one guitar a year which are usually 2k+ each, plus very expensive clothing and I spent about 100 a week on food roughly. However, 5 years ago when I was earning half that amount I wouldn't have dreamed of spending so much and would consider my spending habits now a huge waste of money. After your existing outgoings, ignoring anything you don't need (such as eating out, designer clothes vs GAP, starbucks instead of making coffee in a thermos etc), figure out how much disposable income you have, remove however much you want to save per month, and whatever is left is what you have to spend on things which make you happy.
I take pride in knowing I am wearing great quality clothes that look and feel good, not to say I am ashamed of wearing cheap stuff, it's just nicer. Set your priorities in order and enjoy what disposable income you have.
One last thing to consider, is that your mum likely has a mortgage, has a kid(s) to look after, likely pays your phone bill and supports you too, so for her she would definitely considering that unnecessary spending as per priorities are different.