How do you know if you have it? How do you discuss with your dr? Do you literally just say I think I'm depressed?

Half the time I feel fine. The other half not so much. I break down in tears randomly. Multiple times a day usually. My baby is 5 weeks old and I have a 2 year old. I mean, I'm adjusting from 1 to 2, I've basically been in self isolation at home since march. With covid going on our financial situation is really shitty. So how am I supposed to know the difference between PPD and just being a sleep deprived, stressed out, feels stuck inside the house, new mom of 2?