😔 PPD or baby blues

How do you know that you have ppd? I am a mom of 4 girls I just had my twin girls Jan 30th they were born premature. I have a 9 yo and 1 yr that I have really great bonds with. My 1yo is my princess I love her so much. Now my twins I don’t feel the same how can I feel so detached from them. I can feel that I don’t feel the same way with them like my other two daughters. I feel like something is wrong with me. I’m afraid of saying something to anyone especially my SO. IDK what he will think of me if I say anything. And telling a medical professional scares me I don’t want anything to happen to my kids. Could it be just baby blues?