How to manage the time

I always make good plans for every day.But,seldom could I make it just as what I have planned.There are always a lot of things distracting me from my own path.My mentor asks me to do this and that ,and the staff who is older than me always ask me to do this and that,every day I am nearly acting as an secretary or worker or assistant for them.However,these roles are all not what I am desired to be,the only role I want to be is a student,I want to spend my time on my study and my research,I really want to do meaningful things with my limited and precious time.While the fact is the endless tasks those people give to me occupy most of my time.In order to learn more things and try to execute my plan,I always work late until one o'clock am,and I usually get up at 6:40 am,because I naturally wake up when the sun rises.Even so,I hardly accomplish my planned things.I do not know whether others have the feeling as mine that when I determine to do something and I really start engaging in it,but others ask me to do something else,I would totally be driven to be crazy,angry and messed up.I have to admit,some skills need to be developed in the process of doing some tasks given by others,but if grasped,it's of little importance to do them again and again.If that,it is a waste of time.Sadly,those people who ask me to do this and to do that,always wonder about what progress I have achieved,if I answer nothing progress,they would direct me to do something in order to gain better result,they are really helpful for this aspect.But if I fail to accomplish what they advises me to do,they would blame me and even suspect whether I work hard.I really want to argue with them that most of my time is spend on the work that they give to me,how much time could I spare to do the things that I really need to do even if I have tried my best to spare more time and sacrifice some of my rest time. I am a little overwhelmed about how to manage the time.On the one hand,I have to do the work others give to me,because they are seniors or my leaders,I could not go against their order.On the other hand, I really want more time to do my own business.Maybe,the situation is very common,the fact is that I do not learn to adjust to it.