I understand that your intentions are good, but they are very misguided. If you do not have time for your current bird, you should not get another. The fact is, they may fight or try to mate, and in both scenarios, you could end up with two birds who require totally separate out of cage time at 3 hours minimum. You should never get a bird for your bird and only get one if you personally have the time and money to deal with 2 bird in the event that they cannot be out at the same time.
Also, any new bird will need to be quarantined for a minimum of 45 days (but ideally, per avian vet, 3 months in a separate air space. While a separate air space is impossible for many, you still would need both birds as far apart as possible (definite separate rooms) . You mention that you only have one cage-- under no circumstance would it ever be okay to keep a new bird in the same cage with your old. That is an accident waiting to happen on so many levels.
This is why it is also a good idea to wait until you are graduated and have a steady career/house etc as well, as life can change a lot when you are young, and birds live a very long time. It isn't fair to them to bring them into a situation when you don't know what the future holds and are struggling as it is (due to the nature of school, expenses, unknown future occupation which may have hours ill-suited for parrots etc).
You could easily end up complicating things much more with another bird, despite the fact that your hope is that they would get along, about 50% of the time, they do not....Additionally, the veterinary, housing, feeding costs etc increase significantly with a 2nd bird.