Playing pants size..

[Tom195]

Hi, I just bought some planet eclipse playing pants off here not long ago.. They are a medium and fit well but I was thinking about getting a pair in large because I need them a bit baggier at the bottom...
Does anyone think I should keep the medium pair or go for a large? I'm 5ft11 and quite skinny so its akward Or If anyone knows how to make them a little baggier?

Thankyou for any advice in advance
Sorry mods if this is in the wrong section aswell

 

[Tom195]

Well I've managed to figure out my problem lol, its due to the padded knees so when i'm on my knees the pants seem to slip up my leg but if I tape just under the knees it stops this ..

Does anyone know any other ways of doing this which is less akward?
Thanks