I wore underwear that was horribly small for me for about 2 years and now i have visible lines How to Remove?

My mum kept saying that it doesn't matter, but those undies really hurts like crap and they are probably for 8-10 year olds( I'm now 14). It's really, really embarrassing when i am wearing bathers and there are 2 lines that shows the tightness of my undies,like it's 2 shades darker than my skin, like im wearing invisible panties or something. How can I remove it?