How to get over rough patches in a relationship/how to get through to a man?

I(18F) have been with my boyfriend R(18M) for 3 years, we’ve recently moved away from home both in different cities for University. We’re adapting but we’re struggling, I think it has to do with the fact we used to be together all the time but now we see eachother once a week at the bare minimum, we used to call every night but now we don’t. (none of this is a problem to me at first it was hard to adjust just a bit of backstory as to why i think it’s hard/different it’s a change but it doesn’t necessarily make it bad). Since we’ve come to University our relationship hasn’t been the best, believe me we’ve had our fair share of rough patches but it’s so different now because back then we were kind of forced to deal with it because we had to see each other in school. Our communication isn’t the best, we argue when we aren’t together but when we’re together we are fine, we are constantly clashing(before anyone asks I have brought up a break up or a break as a possible but it’s just not something we want to do). We’re both doing things wrong or things that the other doesn’t like, like I know that I need to try be more understanding and think before I speak when I’m mad and I’m working on it and his problem is he doesn’t text me good morning or goodnight anymore ( i know it’s
minor and stupid and i get annoyed that he doesn’t hence the understanding part because he does text me eventually and i could always send the text first too), he takes hours to text me back, when i try to communicate my feelings about something he can kinda shut me down. I think we’re both going through big life changes and it’s normal for us to bicker and for our relationship to change but I want it to change in a healthy way. I asked my cousin who’s older than me(F23) and she said it’s normal for rough patches even if they are this long but

I just want to know how do i or we fix this and find a new healthy normal? What are ways you recommend I try fix this? How do I have the conversation and have it be effective? As men how would you like to be approached on a topic like this?
Because I love this man and I know he loves me and I want to try my best.

TLDR; boyfriend and i of 3 years are having a rough patch after weve moved to university and our relationship has changed from our old normal which may have caused arguing. How do I fix this rough patch?