This is likely not associated with the heat cycle. Although, do know that just like a human, a poodle in heat has internal water retention which causes swelling -- which can put additional pressure on the bladder depending on the placement of the uterus.
The other issue however is NOT necessarily associated. I'd talk to a vet before you assume she has lost her house training. This sounds like something else. Generall Poodles do NOT like to make mistakes ... though I am not a Mini expert ... I do know that my dogs get a look of embarassment when they have an accident (again, humanizing the issue but you know what I mean).
I'd monitor food and water intake to see what is going on, potty more than regular, and if there is any loss of weight, dry mouth, etc. get the dog to the vet for a discussion.
Not to be paranoid - but better safe than sorry in our house.