Confrontation???

Hey ok, so me and my boyfriend have been together for almost a year now and we were so close. He was my best friend. Lately ive felt like i just bother him but when i try to back off a little he gets upset. For instance, we had a great weekend, he knows i struggle with anxiety so he helped me through a panic attack, but monday comes and hes out with his friends and hes taking hours to reply, doesn’t communicate about what hes doing, just completely forgets i exist. I know if i were to do this to him itd be a big deal. So last night i opened his snapchat and didnt reply because we had just been sending face pictures (which isnt normal for us not to have convo) and he woke up this morning mad at me for not answering. This isnt the first time but idk how to bring up how to communicate without it being an argument.