College. I'm 16 doing level 3 IT and in the English school system I'm in year 12, not sure what the grade would be but I think it would be 11th grade for you. not too sure

Edit: looked up the grade rating system and its done by age groups, that said I would be in 11 and 12th grade due to there being any age allowed into college, it's just mostly consisting of 16-21 year olds though.