Am I wrong to feel unhelpful?

You can only handle what you can handle. We're all different. I'd run a mile I'm afraid, learned that the hard way in the past, allowing people to become dependent on me, and not being able to keep it up.

She needs a Mum's group. Meet others in a similar position to her.

Oh, the poor girl, brought up in care, lonely and desperate for company. Why don't you suggest she joins a Mums and Tots group (obviously for after the birth). My husband worked away when my children were small and I joined 4 groups in my area and made some lovely friends. She needs to find some friends of her own, and meeting other new Mums is relatively easy these days, as there are so many baby activities that she can attend (Baby Yoga, Little Movers, Tumble Tots etc).

Great advice above Feeling

It's rotten when you've always been a kind, helpful person and your energy levels are now sapped (for whatever reason) so much so that you have to change your behaviour.

It goes against the grain to not do as you normally would but equally it's not wrong to give yourself a bit of looking after at the moment

Aww poor lass, she just wants company and a bit of guidance by the sound of it BUT it shouldn't be at the stage where you're feeling this as pressure.

I would help the girl in so much as listening to her, giving advice but draw a line, you have to be kind to yourself as well as to your neighbour.

We all need a friend at times in our lives BUT we also need to be kind to ourselves....

I feel sorry for the girl but you should not feel guilty, you have pointed her in the direction of help.

I have a similar problem, I dread seeing my neighbour but apart from making excuses and suggesting answers to her problems I don't know what to do.

Goodness! I could have written this at some points in my life!
Do not feel guilty - get rid of that right away! She is not your responsibility!

Having said that, it would probably do her and her baby a great deal of good if you could do a little, so think about what you can do and set boundaries. It may also help you, as if she has boundaries she may be less likely to call at the wrong time. I remember my mum doing this, and I learned from it.
So these suggestions are about you taking control, rather than feeling overwhelmed / guilty.

If you possibly can, ask her in one day (or a cup of tea in the garden) and, without disclosing too much, tell her how you have a lot to do, a family that needs you, and that it tires you out. Tell her that you have little spare time for yourself, but it is pleasant to chat occasionally.

I wonder if you could say something like: Oh yes, we can walk / bus into town together, but then I have to..... That would give her a little company and take you very little extra time.

I think it possible that if you can do that, you can then say, without guilt 'How are you? Sorry I'm in a rush today' rather than hiding!
Good luck

Don’t feel guilty. You have your own life, your own family. I have a neighbour, widowed, no children or grandchildren, who knocks on my door, and I have to confess, many a time, I have hidden from her. I know it sounds nasty and mean, but when you hear the same story over and over again, it gets tedious. I understand how you feel ?