How can you talk about stuff so it doesn't come across like you're complaining?

Hard to do in type, in a place such as this. I think the idea that we are complaining is often how it is perceived by the other person and not always the words used. Hard to control another's perception.

I think people understand how hard life is at the moment. So i don't suppose anybodys expecting constant positives in casual chat.

Probably best to compartmentalise subjects into brief summaries.
Home.
Work.
Personal.
Plans.
Hopes for the coming year etc

I would just vent. If people can't deal with it that's their problem.

I always begin with "Well, your mom says--."

Complaining is not a thing to always avoid. If it's compulsive that sucks. But sometimes things just needs to be said and doesn't need to be perceived as negative.