How do I reply to my boyfriend who took 18 hours to reply?

You intentionally chose a boy who is too young to feel that a "relationship" is a responsibility. He's at an age where "It's fun when I see you" and that is actually appropriate for a 16 year old boy. He is who he is at this point in time and that's.. .well... a boy. He'a BOY, honey!

It's likely he didn't really feel he needed an "excuse" not to have continued the conversation as he went about his adventures. It's something to note, for sure. Maybe he's not going to be the sort of boyfriend you want.

From the perspective of social psychology, the length and the timeliness of a reply should correspond to those of the original message. But I hear your point that you'd like more prompt communication. So I think a reply should be "Hey. How's your day going? We'll talk about that another time."

You need to meet with him in-person and tell him your observation about the timeliness of his message (but don't mention anything about his activity in Snapchat and video games). Let him know that you're unhappy with how long it takes him to reply. Finally, mention that you'd be very happy to see improvement in this area. Suggest an approximate timeframe for ex: "I understand that you have a few things to do, but I would be really happy see a reply from you within a couple of hours."

He is really young the thing I can tell you is that he is too young for a serious relationship. I'm sorry to say but he really doesn't care much he just wants to play video games and go snowboarding and have no responsibilities right now. You are more mature and are looking for something more serious. I'm not saying it won't work I am more saying that maybe it could change when he gets older if you want to wait that long, but right now he doesn't have a care in the world and you do. You are two different people, and he thinks that you will wait for him and that you are on his schedule you need to make sure he knows that you rent that you re your own person. that you ill do what you want and that you will not wait for him to reply because you are on your own clock and you have a life to live too. You shouldn't be waiting for him. I say this but on the other side if you want to you can but I feel like you will be waiting for a long time and that will ruin the reputation you give to love at such a young age. You probably think that love is the greatest thing in the world. and it is but being in love with the wrong person can change your whole perspective on it and ruin it for you. SO my advice is to just think smart and know what you want from a relationship and if he isn't gonna give you that then it's not meant to be honey.

What more was there to say to each other?. He texted you "good morning". You texted him back in a like manner. He then asked "how are you?", and you answered him. Then (oh, horror!), he didn't text you back! Why should he? There was nothing more he wanted to say to you right then; the conversation had come to an end.
For how many hours did you want the texting back-and-forth about nothing to continue that morning?

I suggest that you won't easily change this behavior but also that people get busy with other stuff and that's life. You can simply tell him that it bothers you that he has so little time for you and could he please respond more frequently (maybe this will help, maybe it'll help for a time then he'll go back to his old ways, maybe it'll do nothing at all) but ultimately you are going to either have to accept that this is the way he is and live with it or if this really bothers you that much then you'll have to move on. Again, you can tell him this bothers you and ask him to change to I kinda suspect it won't.

DON'T

If you want him to answer quick just say I’m pregnant and he’ll answer immediately

What's the deal? He's sixteen years old. That's all you need to know. You need to find someone closer to your own age.

Take as long as you want to reply back to him.

He's just a kid.