Mild depression. What exactly it is.

Hi, i am in a long distance relationship with an amazing man that i love. We are not getting enough time to talk (he is busy most of the time with family and friends). He feels its okay if we can't talk... we can do so whenever possible. I strongly feel like talking to him at times. It has been a week that we couldn't talk much so i was upset yesterday. He made it up to me and today again we couldn't talk. My anger builds up and it resulted in a lil discussion and i couldn't stop crying... i have been crying very easily since some time... i don't want my mental peace and his to be disturbed in any way. I feel like i am suffering from mild depression... can anyone let me know what exactly it is. Also i am crying whenever i feel angry.... and easily getting upset. I need help.