Yes, you will survive, but if you don't feel good, you don't have to go to school. If you have been passing any waste thru this 15-day period, even your diarrhea, SOMEthing is working right. But long-term constipation is a tough thing, it can be resolved several ways, which your doc will probably figure something out for you. You may ask your doc to test you for various bacteria infections that can happen in the bowels, in case something specific is causing it. I've had both constipation and empaction, they both feel similar, except if you get empacted, you'll start vomiting, and also empaction involves a lot of stuck waste and may take a couple tries to get it straight.
I will tell you what you can do in addition to what the doc suggests. As a regular thing to prevent most types of constipation in the first place, the three main things to keep digestion running smoothly is, drink plenty of water (maybe five glasses a day), exercise regular (helps bowels move easier), and get enough fiber foods (whole grains and vegies). Also, introducing probiotics to the body, especially after the last round of taking antibiotics, will help, which includes Acidophilus milk or Activia yogurt from the grocery store for a couple weeks, the "good" bacteria in them helps break down waste.
For immediate relief, there are three approaches, depending on the situation. One is enemas, see if that breaks loose the blockage. Two is if it's right there and ready to come out, you can buy Baby Lax at the pharmacy, they're a little box of ointment tubes, squirt two in, and the stuff will come right out, repeat as needed. Three is what they would do for you in the hospital, which is to cover your hand with a clear plastic glove and put lotion or plain KY jell on the fingers, and carefully pop out some of the waste, and that will allow the rest to follow... similar to the baby lax only gentler. The baby lax will cause you to have a strong muscle push and the ointment will ease passage of any large waste, but it's pretty intense.
Sorry you are having this, to me it's a scary thing, and you SHOULD definitely go to the doc becuz you may have a bacteria infection or food poisoning going on in there that will need clearing up with medicine. Plus he may have MUCH better ideas than I'm giving you on how to get things back to normal, and he may decide you need an X-ray to see just how bad things are getting in your guts. I just didn't want to leave you without any solutions.