Ok finally getting around to following up on this venting issue.
Basically I don't believe my sink, or plumbing, vents as well as it should. Sometimes using the sink it has a bit of stink to it. Making me believe the air is coming back up where is should not. The P traps are working and full of water but once it starts running it puffs up.
I've put together a drawing to help visualize how the plumbing is setup in my house. I think I need to add a pipe (the green part) higher up and across to let the air out.
I still need to check out the link
@FLSTC provided.
View attachment 42382