Opposite of anxiety disorder ?

Yes, there are disorders that cause people to not care about the consequences of their actions (or inaction, as the case may be), such as depression, but I don't think that's your problem unless you have other symptoms. I don't think there is anything wrong with you that you don't have control over.

Procrastination and apathy are very common, especially among college students. It sounds like you don't make your studies or other things a priority until you absolutely have to. You say you can't help it, but you can. You are just telling yourself you can't so you don't have to take personal responsibility. Putting off things that you don't want to do gives you a pay-off: you don't have to do it right now. That test or assignment is future-you's problem. Screw that guy, right? Only, you're going to be him later.

Have your grades been suffering because of this? If not, that may be another reason. If you don't have negative consequences to your behavior, you have no reason to change it. Yes, cramming for the exam the night before is unpleasant, but apparently not unpleasant enough. Were you this way before you went to university? Or is this a more recent thing?

My advice would be to get organized. You say you miss events because you forget. Keep an event calendar and write everything down: events, tests, assignment due dates, etc. Set goals for yourself. Say that you will start studying for a test earlier than your normally do. Start with small steps. Say that you will read thorough all of your notes a week before the test. Then the next day, say you will read half the chapters that you need to read. The next day, the other half. Break up things into smaller pieces so they don't seem so overwhelming and you won't get as tempted to put them off. Maybe join a study group so you are accountable to someone other than yourself before the test. Make it where you don't have the luxury to be lazy. Once you start doing things on a schedule, you may find that it is actually more pleasant than putting things off because you don't have to stay up all night before the test.

If you do think you are depressed, go to the school psychologist and talk about it. But even if you are depressed, that doesn't mean you don't have some control over your actions if you push yourself.