i am about to tell this girl i like her in 2 days?

i really like this girl, i have the strongest feelings for her but we only know each other for 4 months. we talk OCCASIONALLY but i am really nervous and SHY ! but i am afraid if i don't tell her my feeling she will leave me and think of me as another person she met at high school and i want her and i to be in touch for a long time. HOW do i say, i like her and and i wanna stay in touch.... other then saying "heyy i like you alot and i am ok if were friends but i just want to be in touch when you graduate" btw she a grade older then me thank you