What can I do to fix/improve my lip incompetence? (Photos)

I’m a female between the age of 18-24 years old and my lips don’t rest closed naturally. I have to consciously lift my bottom lip in order to have my mouth closed, but this causes a little dimpling around my chin. I have straight teeth and have never had a gummy smile; nor have I ever been a mouth breather. I do have a minor open bite however it is not my tongue that causes it (as my orthodontist confirmed to me) I’d like to know what I can do to improve this look cosmetically.