Dear my suggestion is that you should concentrate on your finals first as Dota 2 is a game and not your life. There are almost 0.0001% chances that you could make a living out of Dota 2 but you can definitely make a living out of your studies.
Now coming over to the point, your MMR is around 3.9-4k.
Its good that you play support roles and it is also good that you are spamming few heroes. If you want to improve your stats, I would suggest you to go for those supports who can get many assists and can also deal reasonable amount of damage. For example, undying, Necrophos, Crystal Maiden, Lion etc…