Depression in pregnancy

Hey everyone. I need some help with something.. These last few weeks I've been beginning to feel depressed again. 
Before my pregnancy, I had mild depression treated with medication. I had been feeling so much better for a few months before baby was conceived. I was ecstatic and over the moon when I found out I was expecting. 
All of a sudden I'm having the same depressive thoughts again. Suicidal sometimes..
It doesn't take much to set me of- I'm having horrendous mood swings and treating people I love badly then getting even more upset when I realise I'm completely over reacting. 
Why do I feel this way again? I'm so happy about my bundle of joy so why am I so sad?
I'm scared to see my GP cause I'm
Already a young mother and I'm worried they will think I'm vulnerable and take my baby away. 
I don't know what to do. My family live miles away and my partners barely at home. 
I do t wanna feel this way. I get suicidal thoughts but is beer do anything. The thought of my baby and brother and sister and mum stops me.  But I also don't want to have these feelings racing through my head. I know I have extra hormones but it's more than that just now. 
I can't take being alone it just gives me time to think about my shitty life. 
I'm scared of myself. Has anyone else been through this? And what did you do? 
I often wonder why nobody wants to spend time with me because I'm always alone and I have extreme money worries.