What are your thoughts on Bio Oil for Stretch Marks?

Okay so I'm 15, size 10 & always have been but recently I' ve gotten stretch marks on my inner tighs, my hips (just over my waistband), down towards my knees (on the sides) & around my . So as you can guess its a little embarrasing because now I cant wear shorts, bikinis or whatever. Just told my Mum about them 2 days ago & she just said she never got them when she was pregnant & she said 'I've heard Bio Oil is good for them' so I'm just wondering is it good to reduce/get rid of stretch marks that are already there or is it mostly to put on to reduce the chance of getting them. I was late in puberty, I was 14 so seemingly the ones on your hips are from 'late in puberty' & on your knees is from 'growth spurts'. Is that true? Also I've only started using Bio Oil & started using Palmer's Cocoa er for Stretch Marks last week & now the bottles gone so which would ye recommend?