Your mum is just being protective, hopefully she will get over it. But sorry to have to point this out, but the bigger problem is that its kinda illegal, if you waited a couple of years then everything would be cool, 5 years isn't really that big of an age gap. If you both really love each other then maybe you should just wait, that's just my opinion though. I say do what you think is right.
I'm sixteen and the guy I intend to be with is 21. My parents don't approve, but I don't care. I really like him and so I'm going to go for it. Love is blind.
I say do what you think is right.