Depression while pregnant?

I am 18, and 25 weeks...Not a day goes by where I am able to feel "happy" the entire time. I'm either feeling self conscious, upset for no particular reason, getting mad at my SO,  or overthinking how im not going to be the perfect mother to my baby. I love my baby so much, I love my life so much, but I can't help but to feel guilty, hopeless, and worthless. When I get upset, I over think every single  thing i possibly can. I can FEEL the sadness going through my body, I get a tingling sensation in my hands and it runs all the way up my arms to my shoulders and all the way back down to my fingers again. I don't know what to do. My boyfriend is dealing with me the best he can, but he always brings up how he can never do anything right due to my reactions. I feel he's going to leave me, or get tired of me because of how I've been with him. My mom passed away in 09, and I've finally started to realize I am the way I am because she isn't here to guide me and tell me everything will be ok. My god mom, who I live with, works in the medical field and she's hardly home which makes it hard to have any mother figure. All my friends have somehow disappeared. I just feel so alone. I don't know what to do anymore. Am I depressed? Is it just hormones?