Feeling like am going to be a rubbish mum

Does anyone else ever feel like they will be a rubbish parent? Am not after getting people to feel sorry for me because i don't want that, I just want to have a little moan, sometimes with the stuff some people say I feel like am better giving my baby up for adoption, some times I even feel like giving birth then giving the up my own life, I can't talk to my partner because he don't understand I just want to run away and be alone, I feel like I've let my little girl down already and she isn't due til November! Just feel so shit and alone