Feeling defeated 😢

I really really really really want to be a mom more than anything! We’ve been trying for a couple months and still nothing. I get so excited about being pregnant and how much a blessing it really is.... then it crushes my heart and makes me depressed when AF comes. We have a beautiful little girl but she’s from my husband previous relationship so I don’t feel like I can do anything with her( like discipline , activities , or really even call her my daughter) without her mom or others saying that I’m trying to be her mom. I genuinely love her with all of my heart and just want the best for her. I have never and will never call her my step daughter ... I love her like she’s my own . Then I get so upset when unfit mothers ( drug addicts, abusive mothers, neglectful mothers) have healthy kids and don’t even deserve to be moms and I’m a hard working loving woman who loves kids and would love to be a mom and I’m having no luck so far😞 I could just really use some advice and kind words ! Thank you all!