Have you done in-depth research about doing a local high school?  It seems preposterous that it would take you 3 additional years to finish high school when you have (I assume) already completed 3 years.  There might be some small requirement differences, but I would be shocked if it took more than 1 year over your normal grad date to complete the requirements. 
 I know this part won't be easy to hear, but you're not depressed because you're apart from your BF.  You might be sad.  He might be sad.  Neither of you are depressed.  You are young people in "love" and you will be sad while you are apart.  Nothing will change that, but there is nothing wrong with you in a clinical psychological sense because of this.  If you feel the need to write bad poetry, do so (just please don't submit it here).  But you will be fine after a few years cool off your teenage genitals.
