Why can't throw up. And I can't look up why because every time I do it comes up with anorexia stories.?

Every time I try to find out why I can't throw up a whole bunch of stories about anorexic chicks come up. I'm not anorexic I actually want to gain weight, I think I'm skinny. But any ways. I haven't thrown up since I was in 3rd grade when I was 8. I got really sick (I was throwing up every hour). I haven't thrown up ever since, Even when my whole family has been sick and throwing up I wasn't . Now I'm 16. Earlier today I made a sub, got done eating it, then I was putting away the bread and it had mold all over it. I'm a little bit of a hypochondriac, and I could not be sick tomorrow (have a lot of plans). So I tried throwing it up before I digested it and got sick. So I ran to the bathroom and tried throwing up for like 5 mins. I tried my toothbrush and leaning over and the only thing that happened I was gagging really bad but other than that I didn't even feel close to throwing up. Now I'm confused/curious why I can't throw up. Oh ya I found out that moldy bread isn't bad for you :) I don't want to know how to throw up. Just I just want to know why I can't.