Sounds a lot like my second pregnancy. Was so busy I'd forget I was pregnant. I'd wonder why I was so tired, look at the bump and remember that was why! I imagine it's very common. First time around it's special and new, and a complete step into the unknown. Second time around you've done it before, plus you have a child to look after.
Honestly don't worry. You will love your second just as much as your first. Maybe not as much to start with, but you have a years long established relationship with your first, while baby is still brand new. Once baby has a personality, and isn't all take (i.e. interacts with smiles and giggles) the love will be the same.
As for jealousy, it's very individual, and doesn't always happen. My daughter was 2.5 when her brother was born. She didn't have one iota of jealousy. Prepare her with dollies, talk with her about what it's going to be like with a little baby (i.e. they might cry a lot, and won't be able to play yet). Show her pictures of her as a newborn. Show her pictures of you with any siblings you have if you have any. Read books and watch videos/TV shows about characters getting little siblings. Then, once baby is here, include her with as much as you can. Read together, get her to fetch things for nappy changes. Encourage her to show baby things and speak to baby. But also try to carve out a little bit of time to spend with just her. Praise her for good behaviour towards baby. All the positivity.
Bear in mind there is likely to be some regression. Toilet training usually, but yours might be old enough to not do that. My daughter wanted to get back into the pram even though she hadn't been in the pushchair for months by that time. Picked up and carried like a baby too. But she grew out of it before long. Just try to have patience and explain why baby needs it and not her.
You're going to do great. Best of luck in a few months!