I like this girl but i feel stuck. care to help?

me and this girl were dating for 3 months before i asked her out. She said "yes" but 2 weeks later she called it off because she didn't want any grief from her parents due to the age difference. Am 22 and she's 18. I don't think it's a big deal but i respected her decision. That was 3 months ago and from there we stayed friends but eventually stop talking until recently. I try not to come on to her and i try to stay in the friend zone but it's getting more difficult. She's a really good person and has really good values and i respect her and her decision. That's why i don't try to come on to her. She's a really good friend but i want more than that. i don't know what to do ... any advice ?