I'd definitely look further into the PND, if you haven't already. Go back and see your GP/HV about it this week.
None of what you say would cause concern though. My sons both co-slept, none of us would have slept otherwise. DS2 was still in pull-ups until he was about 6 and still has a night light, he's scared of everything, including the dark, so it's easier that way. These things are all quite normal.
You didn't fail at anything, your son has a medical issue, tongue tie is a well known barrier to breastfeeding, that's not your fault. Anyway, many people choose not to or can't breastfeed, it's not failing, it's just doing it a different way.
As for not doing many things with them, their world will not collapse because they didn't go to an open day. But I agree that getting out and about can help you when you're feeling low, as hard as it can be, the satisfaction you get from doing it is huge, even if it's just a walk to the local shop/park and back.
I love that you listed the good points, your children sound loving, happy and well loved, that's all they need.