I'm a college freshman, too, and considering that you've had mental problems in the past, I'm guessing it's depression. Your reactions aren't the norm for a freshman, and the fact that you're bursting into tears, not sleeping, and unable to cope with the tiniest of matters indicates that it's more than a simple adjustment problem. Mental illnesses are notorious for flaring up in times of stress, when you don't need the extra toll on your nerves. I have OCD, and possible cyclothymia, and believe me, I've had many breakdowns these past few weeks due to change, lack of structure, annoyance with people, and instability. Not homesick whatsoever, but taking an OCD-er out of their comfort zone into a place that doesn't involve routines, isn't exactly the best situation!
If you ever want to talk or vent, I'm here; I understand completely how hard it is to be a student with a mental illness. I struggle to get through each and every day, which isn't helped by the fact that I'm in the process of switching meds, and I'm on less Zoloft, so I'm having a hard time balancing my frustration... And then, we get the added bonus of being surrounded by people who have no idea how much we have to suffer.
Good luck and God bless!