I'm a childless Aunty & Godmother too. Definitely not by choice, although I don't see how that matters?
I spend a lot of money on them all at Christmas/Birthdays. The third oldest now had a DS & one on the way, so I buy for her DS as well & will for the baby. The eldest one lives with me sometimes I usually get a card from them. The eldest has occasionally made something for me
(Cookies etc).
Nieces & nephews I'm lucky if I get a card & I sometimes get a photo of them
Opening their presents (they live overseas) but it's not unusual not to even be told they've received them. I end up having to ask my mum incase I need to chase it up with the post office. Something little, would be nice, even a card or 'text thank you' would be a start. The kids are old enough to text me themselves these days too.
I think my DB & SIL are really rude
I do it for my Mum (or rather to keep the peace with my mum.
The other set of god children I buy for are teenagers now, I still spend a lot on them, their mum usually buys me a token gift (book or bottle of wine type thing) even though I usually buy her & her DH individual 'proper' presents too.
It's partly the money. Christmas ends up being very expensive for me, but without anything to open or look forward to myself. It's really the lack of thought that upsets me.