shoulderpads on Racesafe BP.... fit?

[NeverSayNever]

i ordered some shoulderpads for my BP, and as I have the childs XL BP, the lady at treehouse said to go for the Medium shoulderpads... I did tell her at the time that im pretty scrawny but she said the smalls were just for little kids.

they arrived this morning and over a fleece jumper i can get a hand under the straps and cant do them up and tighter... so how tight are they meant to be?

this is a pic of me -

 

[NeverSayNever]

update- i spoke to treehouse and they said if i went to a size small it wouldnt provide enough protection over the shoulder... and they have advised me to stitch a tuck into the elastic, this is a tight as it goes...