1. How the heck do I know he is full?
It's hard, isn't it? But usually it would be that he would seem satisfied when he's finished eating and burping and not rooting for more food. Are you feeding from one or both breasts at each feed?
2. I have low supply and I'm taking herbs, meds and tea. I have a lot of anxiety that he isn't full enough when I lay him down. So when be fusses and I fed him 1.5 hrs ago how do i know if he could be hungry? Any of you experienced this and how do you deal with it? Do you just trust that its not? He is tricky to read for sleep signs so I end up relying on the clock.
If you're not sure if he's full or not when he finishes, how are you sure you have low supply? Who told you this and advised all these steps? Did they suggest to add some pumping sessions too? Has LO been checked for any oral issues (tongue ties, lip ties etc) that can affect milk transfer and thus supply? Sorry, that was a lot of questions to answer your questions, but I feel we can best deal with things if we have a good all-round picture of what's happening.
Usually, if LO has finished feeding and is satisfied, you'll then be looking out for feeding cues around 3-4 hours from the start of the previous feed.
3. What is active nursing exactly? LO will nurse and nap it seems. Sucking away and once I have a let down open his eyes, put his head back a drink. My let downs aren't constant. Is he napping or resting or what? If I wait until he pops off he will nurse forever and I can't get anything done.
Active nursing is where there is sucking and swallowing, usually in some sort of suck-swallow-breathe pattern. Don't worry. No one's letdown is constant. Milk is created by LO sucking, so any sucking and swallowing at the breast is a good thing. Between letdowns, LOs will take a bit of a rest time as they milk isn't flowing as quickly.
I can understand how you feel with a LO who doesn't let go. My DD didn't used to unlatch when she'd finished feeding either, so I'd usually pop her off the first side at the point where she seemed to be dropping off and put her onto the second side.