HELP.. i'm so anxious/depressed all the time?

I just feel like my life has lost meaning. I tried being a teacher, and I was told that I was not up to standards, so now I carry this with me wherever I go. I'm just not used to failing and I can't help but continually dwell on this failed career. Now I feel like I can never be a good teacher, because I just didn't know how to handle my class. Right now I'm working in another career, but I just don't feel fulfilled in my job. I'm always anxious all the time... and I'm always crying (at home). I just don't know what to do with my life and I feel so lost and trapped. All I want to do is just get married and have kids, I really don't want to work, and I can't see myself doing anything really, but I need to in order to make a living and survive. I just don't understand why I don't feel fulfilled.. it's like something is missing in my life. I have an amazing boyfriend and lots of friends, but I'm still always sad... WHY? I really don't know what to do and I really need to talk to someone because I keep feeling suicidal and I really want it to go away and it never does... I just always feel hopeless. PLEASE HELP