not what's wrong

Last night I woke up crying, and tonight I just did the samething but cried a lot harder ..... I tried not to so my husband wouldn't notice .... 
I don't know what this is I just feel sad.....I had a period last week so I'm not pregnant .... my family lives very far away... my birthday is coming up and my twin sister is back home ( I miss her )
Is this maybe depression ? I know