Hi OP
As others have said, you ending your life will leave a legacy for your child.
You say your mother was not very emotionally available, and this has left you with a mother wound. It sounds like you may have also left you contending with horrible thoughts and feelings that are difficult to bear. It'll probably help you, although it may be very painful, to explore these feelings with your therapist - the more you put these feelings into words, the more your ability to contain them will grow.
You're worried about the suicidality - you're also a mental health nurse so you know that it's probably unlikely that anything will be actioned via social services unless your baby is in danger of serious harm.
It's possible that in imagining that social services will take your baby is likely a fear of catastrophic loss, but it's a loss you have probably already felt - the disappointment and loss of not having your mother be the mother you hoped she would be.
Sometimes it helps to say to your therapist - I really want to talk about some very difficult thoughts and feelings but I'm scared of the consequences - have that conversation with them - if they are a well trained psychodynamic therapist, they will work this through with you until such time that you trust them. It might be trust in your therapist that is the issue rather than the thoughts themselves iyswim. I'm not saying the thoughts aren't important, just that there might be other dynamics at play too. And a good enough therapist will be very used to this.
Some people with a mother wound find it helpful to actively seek out mother figures - good ones - that are older and wiser, and that are kind.
Take care 🌹🌷and look after yourself - rose Otto massage oil - few drops in a carrier oil - if you like the smell, are not allergic to things like that (you can make this decision) - can really help when you've got a baby. I think you said LO was 9 months - some people feel really tired when their baby is this age, so be kind to yourself. You might have to make a bit of an effort here if your own mum isn't / wasn't around for you.
Another thing that people find helpful - your mind is the sky, your thoughts are just the weather - ooh look there's a stormy one, Oop we have a hurricane coming. Oh look a sunny day. It's a little bit detached but some people find it helpful.
That's a bit long! Take what fits and leave the rest 🌷🌷