Is it different when you have a second child?

Did you not feel as connected to the second child? Like the excitement wasn’t as big because you’ve already been there, done that with the first child? I’m a first time mom, however my SO isn’t so I can’t relate to how it is when having a second child and if the excitement is different/less.

Backstory: my SO of 4 years has a child from a previous relationship, my stepson is 8 now. I hear all the stories on how good of a dad he was, especially when SS was a baby. How he would stay up all night soothing him, spend every waking moment with him and overall couldn’t get enough of him! I’m definitely not suggesting that him being completely invested in his son and was a very active father is a bad thing, I always admired that about him and was a big deciding factor on my end to have children with him because before him, I didn’t want children.. then seeing how good of a dad he was, how amazing it felt to have my step son in my life made me want to have a child and give my step son a sibling that he very much wanted. Now my daughters 14 months and my SO is not interested in her at all! The first thing that kind of threw me off was the night I had her, I had been up for 36 hours straight at that point, it was 4:00am and I was just defeated. I was so tired I was scared I’d fall asleep holding her and drop her, I NEEDED to sleep, I woke and asked my SO to take her for a bit and he straight up said “no, just let her cry” in a HOSPITAL full of newborn babies with moms trying to get there newborns to sleep without having to hear mine cry, not like i would’ve let her anyways but still. I thought it was just him being tired and brushed it off, then began to be a battle to even get him to do a diaper change and I gave up asking at 6 months old, he would huff and puff, gain attitude and I was just sick of it. He doesn’t feed her, never made bottles, never stayed up with her during the night or has even woke up with her in the morning to allow me to get some sleep. He doesn’t spend time with her, he hardly acknowledges her existence. She lights up when he walks in the room and he just sits down on his phone and it really hurts me to see that! I am honestly shocked at how it’s turned out because he’s such a good dad just not to my daughter! Christmas, her birthday he didn’t get her anything but showered step son with gifts, ok, I get she’s not old enough to notice... but still, he could’ve bought a stuffy or something as it’s the thought that counts! I’m so tired of feeling like a single parent, I never get a break! I am so sick of asking for his help, I shouldn’t have to because he’s her parent to! I’m not asking him to do everything, but it’s gotten to the point if I’m doing dishes or something and she starts fussing he will either leave the room or call me to deal with her! She’s walking and very mobile now, she’s a happy and easy baby but I can’t even shower without putting her in a chair in the bathroom, I vacuum with her hanging off my hip while he’s sitting in the living room. I could leave her with him but then he gets bitchy? Thank god my step son is a god sent, whenever he’s around he will try to give me a hand with entertaining her while I cleanup or making a meal but it shouldn’t have to be that way, my step son loves playing with her but it’s awful to think I can only get stuff done when he’s around. Of course there no obligation for step son to do these things, he just enjoys it! But it’s sad that an 8 year old child is more help than the parent of there siblings! I’ve tried to talk to him about all of this many of times but it always ends in a huge fight and he twists everything around on me, I just don’t get it! I’m not even asking for him to do the boring parent things like changing diapers, feeding, putting to bed etc I just want him to connect with her, play with her, overall enjoy her because she deserves to be noticed too! Is this normal behaviour or am I completely crazy?