Will my braces ACTUALLY be off in a year and a half?

I am 16 years old and am a sophomore in high school. i have had braces since last march so i have had them on for a year and 3 months. when i first got them on my orthodontist said i would have them off in 18 months. So far not much looks very different. i still have quite a bit of gaps and i am scared i will have braces for a long long time. Is it possible he is just working on my bite and jaw before he closes the teeth together? I am not really sure what to expect. they are ceramic ones too and i heard that makes a difference. Please give me advice! Thanks!