Having a baby completely changes the way alot of women see their future. Its exhausting, and when theres no or very little support it can be over whelming. Add into that the influx of hormones and its very hard. There could also be an element of post natal depression, its not always obvious to pick up on and can last months, even years to a degree of some sort.
It can also be scary. Suddenly there is this little person who is 100% reliant on you. Life, for her, has changed forever.
I've seen so many times, men saying if only she'd asked me i'd of done xyz. Point is though, we are sick of asking. It should just be got on with. Washings piling up - wash it. Dinner needs sorting - sort it. Carpets need hoovering - hoover them. Don't wait to be 'asked'. Did you fall into the trap of only doing things she asked you to do? Because when women have had a baby, they need an adult as their partner, not another child who has to be told everything they need to do.
Also, how long have you been engaged? After getting engaged did you do anything about planning the wedding with her? Or just get enaged and leave it there? Again, she could be evaluating how much you really want her and want to be a family if you've done sod all about that after proposing. I don't mean to be harsh, but again, so many men do the propose part and then go silent. Almost like their job is done there.
She needs to feel special, especially after the baby her body will be changed, even if its not noticible to you, it will be to her. She needs to know that you love her even more then you did before as it is quite a shock to the system to be honest after the baby comes and things don't quite back to what shes used to being her entire life. it takes time.
Going forward, you need to listen to what shes telling you, and respect it if she says she needs some space. And actually put into action anything you say or promise. Words are easy. Its the actions you do to back them up she'll be taking note of.
Baby needs clothes? Tell her 'lets go now and get some'. She says shes tired, take baby out for a couple hours so she can have time to herself. Just try and do anything you can to lighten the load. And most of all, make sure she knows how much you love her, and that yes, she is in fact the centre of your universe (along side your new baby).