How do I know she really loves me? ?

Im 17 Years old. now dont say its to young but... ive bn with her for a wile... we hav everything in common. i just proposed to her March 27th. I deeply love her and i feel verrrrry protective of her (but definitly not controling).. im willing to give up everything to be with her for the rest of my life. We have never had an argument over anything. We say we love eachother everrry day. this i know is love. not infatuation. and wen shes gone like with frnds im depressed, sad, and miss her so much.. i worry about her.. and i cant trust ppl arnd her. i trust her with all my heart tho. but... how or wat do i say to know how she feels. i really dont kno wat to say to her to know.. I will say anything to her. I just want to know how she really feels about me.. anyone help??? any advice???