I think I got my 1st stretch mark! What do I put on it?!

Nat
I've been using BioOil every night since the beginning of my 2nd trimester and I'm 31weeks and I just got two faint indented pink lines on my stomach. I'm not sure they're stretch marks but I want to know what works to put on them after I get them?  bio Oil doesn't seem to get absorbed it ends up on my shirt and sheets so I'm looking for somethig else.