can anyone recommend me a story where the girl is older than the boy

You must have most probably read this already but here goes:
https://www.webtoons.com/en/romance/to-love-your-enemy/list?title_no=2114

Here some coloured ones
http://www.mangago.me/read-manga/back_to_the_highteen/
http://www.mangago.me/read-manga/four_years_apart/
http://www.mangago.me/read-manga/que_sera_sera/
http://www.mangago.me/read-manga/nineteen_twenty_one/
http://www.mangago.me/read-manga/summer_breeze/

http://www.mangago.me/read-manga/age_matters/

just in case you haven’t read it yet: http://www.mangago.me/read-manga/summer_solstice_point/