If she's clearly moved onto the point of wanting someone else, thinking about you is NOT a sign that she can come back to you. I still think about my ex's in regards to memories, they've helped shaped me for who I am today so I don't have full regrets regarding all of them.
However, you must move on your self, waiting and hoping is only going to leave you upset or jealous.
If you move on from her to someone else and she wants to come back to you, than from there you can decide what you want.
Let her be happy, and let her go my friend.
Yesterday is history, tomorrow is a mystery, but today is a gift, that's why it's called the present.