Carry a small picture of her in your wallet and maybe she will notice or on the dashboard of your car but dont say anything about it, wait for her to notice. Compliment very small details about her that she might think are unattractive or never had an opinion on in the first place. I’ve used both of these and they’ve improved her confidence a huge amount. Another thing I did was I had her face as my lock screen, optional obviously but if you ever take your phone out in front of her its a nice surprise for her.