Most importantly, you need to make sure that you are drinking enough water. If your body does not have sufficient hydration, you will not be able to produce milk. Carry a water bottle with you and refill whenever you can. You should also be maintaining adequate nutrition and calorie intake as well as adequate rest (obviously hard to do as a college student with a five-month-old baby).
In your posting, you do not mention how many times you are able to pump each day (and how many times you are breastfeeding). Your goal should be to pump each time your baby needs to eat (even if you are not with her). So if the baby is drinking six times each day and you are with her for only two of those, you should be trying to pump four times. Many women find that they are able to get the most milk when pumping in the morning (either at the same time as feeding the baby or right afterwords).
There are many over-the-counter and prescription medications that are available to try to improve milk supply. Research is lacking on the effectiveness of these medications, but none of them will work without the attention to fluids, rest, and nutrition mentioned above. Over-the-counter options include milk thistle, mother's milk tea, and fenugreek. Prescription medications include reglan and domperidone. Before trying any of these options, you should discuss them with your doctor or a lactation consultant to make sure that there are no contraindications.
Good luck with your baby and your studies!