I'm assuming that everything in your post came up during the meeting - so what I would do is send a follow up meeting to your manager (and HR?) showing what you understood was said, and asking for more clarification on the things that are unclear. I'm putting the bits in Italics to show you what I'd referencing from your post - obvs don't include those bits in the email.
Start the email saying something like - "Following up on the meeting yesterday, thank you for the feedback, I just wanted to summarise what we talked about and ask for clarification on a few points.
I was told my work wasn’t perfect when I came back as I was missing small things (work in a professional role) but I was steadily improving as the months had gone on.
I appreciate that you have acknowledged the improvement in performance I have made since returning from maternity leave. I feel that I've worked hard to bring all work up to a professional standard and xxx xxx (insert something positive specific to your job performance here)
I was told of the direction of the company and that manager was looking forward to us all embarking on this next phase of growth together.
This was a really important part of the meeting. Can you remember specific words and phrases used? You need to add a line in summarising this to show your manager that you are on board with the 'next phase of growth' and are going to be a team player. So something like: I understand the direction the company is going and the need to do xxx and xxx together as a team to build xxx xxx xxx (whatever is specific to the message they were pushing at that point) Don't underestimate this part of the meeting - they were telling you their goals and expectations before the hit you with the whammy that they are not sure you are up to this 'next phase of growth' - make sure they know you understand there is a team goal and you are ready to be part of it.
I was then told it would be a good idea to re address the balance of my home and work life as it’s probably too much tipped into the home life at the moment. I have no idea what that meant, I leave to do nursery pick up but I’ve been told (by this manager) that that is fine.
Ask for clarification on this while also making sure they know that you are working before and after you come into the office, and double check again how the nursery run every day is being perceived.
I was concerned to hear that there is a feeling that my commitment to the position is being affected by my work home life balance. I would appreciate more clarification on this so that I can address any issues or concerns as soon as possible. I was told leaving to pick up my child from nursery was acceptable, and I have made sure to work from home before and after office hours to compensate for an early departure.
I was also told I need to build on being more robust so they can send more work to me steadily. I had no idea I wasn’t robust?!
I'd also like clarification on being told I need to be more robust. Could you be more specific on how that relates to my performance targets and what you would like to see from me.
My advice would be to watch how you are interacting with colleagues because the work life balance and robust comments sound to me like feedback that has been fed to your manager from your day to day interactions over the last six months. Do you come in exhausted - talk about DD a lot - make a big exit with how you must rush to get to nursery? That sometimes winds up colleagues especially those without kids who resent parents leaving at set times every day. I don't think it's wrong for you to have this accommodation but be careful how it appears so people aren't grumbling about you to the manager.
And re the robust - again sounds like colleagues complaining that they can't risk asking for things or help in case you get overwhelmed. Do you seem frazzled a lot at work?