To think that I am just a nuisance to my children

Do you like your children?

Do you enjoy their company?

Look after yourself and build a life that is not about them. Join a choir / walking group / book club. Eat well, exercise well. Fill your own cup.

My depression is horrible and not something I would wish on anybody.

so you’ll understand then that your son, also suffering from depression, will be suffering

I say this gently - if your children wanted your company they would seek it out. Children don't ask to be born, and life can be difficult. They don't owe us anything, so you have to manage your expectations.

All we can ever hope for is that our children find happiness.

Being available to them when they need support, a sympathetic ear, someone to feed the cat, is our ongoing duty as a (good) parent. What we receive in return is very much up to them.

We have to fill our own lives as best we can with things that bring us joy and fulfilment wherever that may lie.

Yes, fun seems to be missing.

My mum has some of the issues you describe. O see her 1-2 x a week. I feel guilty for saying it can be a bit draining. Are you able to plan fun/ light hearted stuff together?

Ok. It's more clear now.
You did your best and are doing what you can to help now.
I don't think your kids see you as a nuisance but they are likely too busy to think of you as much as you think of them. I am in the same boat! Most parents of adult kids are.
Perhaps it might benefit you to do more outside your family.

i too think it’s your depression talking. It sounds like your children didn’t have the best of childhoods due to the complex adult problems they were surrounded with and that probably will create genuine distance, but there is nothing you’ve said that suggests they see you as a nuisance

depression can make you feel you’re the main character but you’re likely not.

Am I reading the same post? You provide what sounds like pretty regular childcare for your daughter. Why are you apologising for yourself?

It’s tough isn’t it; you were their whole world when they were little and now you’re a bit part.
My advice is do the things that genuinely bring you joy, actively seek them.
Eat well, exercise well and socialise well. This is a different chapter of your life.
You did a good job as both your children are living independent lives. Enjoy being a grandma and try not to dwell on what you haven’t got.
Do your gratitude every day, it really does help with depressive thoughts and habits.

I have one remaining parent and while I invite her for Christmas and see her regularly, she's not exactly a priority in my life - but I don't feel that I was hers when I was a child, so it's fair to say it's complicated.

You're likely seeing your relationship with them and your worth to them through the lens of your depression.

A couple of ideas to improve your relationships :
Do you phone them both and show interest in their lives?

Have you ever spoken with them about their experience of childhood? And listened to what they have to say? Without explaining or justifying yourself. Have you taken responsibility and apologised when you've made mistakes?

Does your daughter not include you at Christmas and Easter on a regular if not always basis? That’s a real shame when she knows you’re alone and you help them.

Your son sounds unable to have the capacity to be different but you can still retain closeness via messaging/ calls and occasional visits.

I guess the question is, do you all actually enjoy being together and what is your relationship like with them and their partners?

My own mother is widowed and elderly and whilst not the easiest company I love her and try to be a good daughter.

Your son is labouring under a mental health illness.

Your daughter is stressed by money worries and balancing work and young children

Cut them some slack