The meaning of my life

I don't know what is the real meaning of my life, and I am looking for it. I tried to find the meaning of my life, but I did not find it. I had a dream in my mind for about 10 years, that is to be a doctor and do something for the people who is living in pain and make them happy. And I thought, the happiness of others which is related to me will make me happy. But the dream became a dream that will never going to be true after I made a little mistake, I chose the wrong major. And after that things changed, I don't know what I should do. I never knew without a power dream had such a great influence. Then I felt blue for a long time, tring to think about the meaning of my life, but I can not get a good result. Then mom told me, "Just let it go, you will know it in the future, what you need to do now is study hard and absorb the knoledge which will help you in the future. And don't think too much." And I believed another sentence" God has a plan for you!" And now, I have a dream which is to make people who loves me happy.