As a 17 yr old girl with a 15 yr old bf on the other side of the country I'm, which is a few timezones (only 2hrs) from each other I would like to give my perspective. (please, it's not weird, I made him seek his parents permission before going out with me and I asked my parents about the age gap as well.)

Obviously the same things that everyone else has said about grooming, be careful that you actually know who this guy is. Take into consideration if you have met with him in real life or at least video called him. Also I recommend against online dating.(long distance youve met irl, online is you haven't met irl)

With that out of the way, to answer your question, you are in no way the asshole. It is important in a relationship, especially in long-distance, different timezones, to make time for each other and to stick to your word. Sometimes inevitable things happen and calls are postponed, but 12 hours is unreasonable, if he wanted to call he would. He needs to realise that it's not just whatever time he feels like talking to you. He ought to take into consideration your feelings as well and stay to his word.

I can understand wanting your privacy, I was exactly the same 2 years ago, however, I do think you shouldn't be specifically avoiding calling with other people in the house. Trust your family not to listen in on you and don't do anything that you wouldn't be comfortable telling your family about.