I just turned 14 and I was wondering if it is better to wait to get my tougne pierced. I'd rather get it now but my mum needs some convincing.

I don't wonder your mom needs convincing. Tongue piercings cause more oral damage then teeth that haven't been taken care of in a while. If you have this done you will have to live for a couple of months not being able to articulate speech until you master talking around the piercing. If it becomes infected, then you will have to be aware that it can cause massive tissue damage in your mouth. Not to mention though, the number of teeth in your mouth that will be damaged, chipped causing dental problems you don't even want to think about right now; but someone, possibly your mom will have to pay to have fixed.

So weighing all of your options, then I guess, yes, your mom should think twice about letting you have it done.

Tick

I'm Fifteen and managed to convince my mother, she let me because its my body and my decision.. and if I don't like it, its easily taken out.
It did not hurt at all, I thought she was just marking the dot on the bottom of my tongue and then she was screwing on a ball.. didn't even know she done it.
I have only had mine pierced for 3 days so its new and still fat.
I can talk and eat normally though, and as for people worrying about it chipping your teeth you just get gel balls to screw on to the bar, they don't chip your teeth.
Just clean it after every meal and you will be set.
And as for speaking I had a slight lisp that was noticeable to some, but it went away after one day.
And as for kissing, I have already kissed someone and it was weird considering my tongue was so fat, but he tended to not mind it, not supposed to kiss for a week after it but hay its still healing well :)
Hope I helped.