So I need positive reinforcement...

Hey everyone... I have been ttc for four months, which I know isn't long, but I also have PCOS... so I'm worried I won't be able to conceive easily... I have a long history of depression and anxiety... so that being said, my fiancé and I are getting married next month, and our kiddos (his bio kids and my step kids) mom is pregnant again... I am to say the least sad... she doesn't deserve those kids and she easily is having another one... I can't help but feel worthless and like shit... excuse my language... I don't know what to do. I'm only 20, but I can't help but feel overly dramatic about this. I know with my condition it's going to be hard conceiving... so I already feel like my chances are dwendling. I mean this woman got off bc while she was still dating my fiancé back in the day and intentionally got pregnant with both kids without discussing with my fiancé first... and now she's remarried, has the two kids with my fiancé, and has two step kids with her husband, and now this one on the way.... she has had two kids... and now she's bumped up to 5.... I feel hopeless. I know I'm only starting out... I know so many people have it worse off then me, but I am taking a minute of self pitying as I feel like it and Im emotional AF (not aunt flow) right now. I took a test as my period is late today, so once I saw via paperwork that she was pregnant, I drove to Walmart to get a test. I came home and took it, negative. Help me... I only have my fiancé to talk to about ttc and he's at work.