long distance relationship tips??

me and my bf live 250 mies apart and due to student stuff i only see him once every couple months. we usually talk a lot but i have no phone and cant take my aptop into college so hes messaging me and im taking like five hours or more to respond. I feel really selfish for only talking to him when the time suits me as he lterally always wants to talk to me. He says he understands, and even apologizes for getting upset about the lack of contact (i feel so bad, its my fault for breaking my phone, not his!). But i feel even though hes so amazing about everything its taking a toll on a relationship that weve maintained for eight months now! So I need advice, quick! I need tips on how to maintain this and show him how much I love him when we barely talk all day so that he knows that hes important and special and our love doesnt start fading away! Thanks for any help in advance (and apologies for my spelling, i am wearing false nails)