*hugs* Certainly get any thoughts of not having milk right out of your head. That way leads a slippery path. I'm not sure of the statistics, but only a tiny % of women can't produce enough milk for their babies. I think I may have said before that the 'full' feeling tends to be engorgement, which means LO needs feeding rather than it indicating an amount of milk that is present. As I understand it, engorgement is caused by excess water in the breast tissue rather than an accumulation of milk. Sometimes it helps to think of the breast less as a glass that gets full and is then emptied as it's being drunk and more as a tap, that there's always milk there to come out, but just needs to be turned off and on
Do you think trying to feed him in a different position might help the wind and/or slipping? Did you get along to the BF support group yet? They might be able to see something we can't which is causing him to slide off.
If your breasts are just feeling warm generally then you're probably ok. If it's more specific heat in a particular area, you might want to keep an eye on that. As Shiv and others have said, ibuprofen is fine whilst BF (happy, it sounds like your pharmacist may need to brush up on their BF drug safety
) if you need it.
As for when to switch breast - if he's fallen asleep on one I might offer that again and see how he gets on. If he seems frustrated or disinterested I might offer the other and see what happens.
You're doing great