Low mood

Hello everyone I'm 37 weeks tomorrow and I am struggling with my mental health mood wise. I'm 34 and have no true friends, I have a loving supportive partner but feel so down and lonely. Had a lot of change recently and my partners son who is 11 is really bugging me with his odd behaviour .... I sounds awful saying it but I just can't take it him and I don't know if it's the hormones or what! I'm just really struggling. Has anyone else had any mental health issues? Just don't know who to turn to or talk to. Thanks x