Daughter won't be an only child much longer

Any mommies with kids close in age ever have a hard time near the end of your second pregnancy with the change in family dynamic? I'm a stay at home mom and my days so far have completely revolved around my daughter. And knowing that our days of just the two of us are quickly coming to an end has been emotionally difficult. I know a lot of it is most likely hormones but it still makes me sad. If any of you have ever dealt with this does anything make it easier? I know it's just a change and a good change at that. But it feels like I'm almost losing her in a way. I kind of feel like I'm grieving. At the same time I feel guilty towards my son. I love him very much and can't wait for him to be here. Any advice would be much appreciated. I'm really struggling.