Why has my boyfriend stopped talking to me?

Hi
So my boyfriend and I have been dating for almost 8 months and I love him to death even though I haven't told him yet. Anyway he has social anxiety and he tends to be the more quieter reserve type which I'm fine with. I also have anxiety do I freak out or worry about things on a daily basis and he knows about this. Right now we are out of college for the summer break and we are living in our hometown which is about 8 hours away from him so we have to rely on messaging each other to keep in contact. I also won't be coming backto school in the fall because I will be studying abroad. However, I'm coming back in the spring and I spoke to him very briefly if he still wants our relationship to keep going since we're going to be separated for a long time and he does still want to be with me. This is my first boyfriend by the way, and I think he had a girlfriend before me, but I don't know. He's also two years younger than me, but age is just a number.

Anyway, My question for all of you today is, Is it normal for my boyfriend to stop talking to me mid conversation and not answer me back?

We usually Facebook message each other because he has bad service where he lives and he doesn't always get my texts or gets them delayed. The last thing I asked him before he stop answering me is if I "can call you instead of texting you because I rather not write You a novel. Lol." And it said he saw the message. I did message him 7 hours later with a "Hello?" though and still got no answer from him after he yet again saw it. Before this message I was asking him if I could tell him about my day and he said he would love to listen. Anyway, my boyfriend hasn't managed to say anything back to me for a few days now and I feel like I probably annoyed him or my texting is annoying him since I try to talk to him at least once a day even with silly jokes or whatever. The reason I think he finds me annoying is because he told me that he doesn't usually start conversations with people and that he prefers text over a call. This is why I usually text him but I do like calling him sometimes too. He told me it was alright if I called him whenever and I have talked to him a few times over the phone though but I'm of course the one who has to ask if can. I'm also the one who usually initiates conversations with him which I'm okay with. I have managed to talk to him about my feelings about similar things to him to let him know how it feels to be the one trying to do everything in the relationship and he told me that he knows and that maybe he should try harder.

What am I doing wrong here? I plan on messaging him tomorrow to ask what happened or something like that if he still doesn't answer me today. I'm just looking for opinions.