Feeling guilty 😔

A little backstory....I have 3 children (12. 10 and 8) with my ex-husband. He is worthless and gave up custody of them 2.5 years ago. I married a wonderful man last September (we've been together over 4 years) and we are actually in the process of having him legally adopt them. My husband does not have any biological kids and I want more than anything to give him one so we are currently TTC. We've had a couple of chemicals and they always make me sad but whenever I talk about it to some people, they always say "Be happy and grateful for the 3 you have". And it's not that I'm not grateful for them at all, I just want a biological child with my husband even though he sees our 3 kids as his already, I want him to have one of his own. And I see so many women struggling on here to even have 1, I feel guilty for wanting another or for getting sad when I have chemicals 😔