I'm 25 pregnant with my 3rd child, i'm having anxiety about it and my moms opinions don't help me any!?

I’m 25 I have a 7yr old girl, and a 3 yr old girl at home, and I’m expecting another girl in October. Since I found out I was expecting I have been a little overwhelmed, especially because we weren’t planning on another child for a couple more years. And I was on the patch. I am worried because I don’t know if we can do it financially. But my honey ures me we will be fine. Since we found out my mom hasn’t been too supportive, she thinks I am going to leave my oldest daughter out. That I am going to let her slip threw the cracks. She would’ve preferred I have an “A” word. Which I would never do. Every day I see her she manages to remind me that I am making a horrible mistake. That I am not going to be able to do it. Just always negative things. I love my mom to death but all of her negativity she has been telling me is really taking a toll on my emotions. I am getting depressed here I am 7 months pregnant and I don’t think I have ever been really happy about this pregnancy, which scares me a lot because I have never felt like this, not even as young as I was when I had my first daughter never not once did I feel like this. Is something wrong with me, is it my moms negativity that’s getting to me? Please help, I’m not in the strongest of spirits lately so if you plan to answer my questions very harshly please don’t. Thank you and God Bless!!