Sometimes even the mini pill can cause milk decrease. Just keep an eye on baby's diaper out put. That is the only certain way to know if supply is decreasing. I know when I'm bleeding, my son is more fussy than normal. Watch with the mini pill. It is common (but not considered normal) for it to cause frequent periods. I had that problem. I was getting periods every 12 to 14 days.
I take the same and have no trouble with. DS3 is always satisfied and is thriving. Maybe your lil one is having a growth spurt. Stay hydrated, rest a lot, eat fruits rich on water and oatmeal will help boost the production.
Once you've been feeding for a while your boobs won't feel full as much as they do right after you start so that may not mean you're not producing.
As far as the baby being fussy, it could be lots of things. He could be gassy or not able to latch properly. I would get in touch with a lactation person to help you out and then if you really think it's a supply issue, there's lots of things that can help that! Good luck to you!
If he is fussy, it might be that he is going through a growth spurt. If he is constantly nursing its his way of upping your supply to help with his growth spurt. A growth spurt lasts anywhere from 4 days to one week.
As for not feeling as full, that is normal after a while.
Here are a couple of sites that might help you. The first is Le Leche League. Try and find a meeting near you. They can help with anything!
The second is Kelly mom. Questions about meds that you are taking or what to eat or not to eat while bf. Growth spurt charts. Great site! Here is the page on that site about when growth spurts happen. Kelly mom
Also, when do you notice that he is the most fussiest? Is it in the evenings? If so, then he will be nursing more frequently, like on your boob from about 5pm on till bed. This is when they tank up for the night. This is completely normal. Make sure you are eating enough and drinking plenty of water but not over doing it.
My dd is 9 weeks old so this is all fresh and new for me too. She is my 4th baby but the last time I nursed a baby was 4 yrs ago so I had forgotten a lot what happens with newborns. Thankfully I have a friend who is a lactation consultant and she also has a nursing support group that I try and attend as often as I can with my dd. I was able to talk with her and that helped.
This actually happened when I had my son. I went on BC when he was 6 weeks, and as soon as I did he went downhill, so I stopped straight away. I dont know whether his colic was caused or made worse by it but I didnt risk it again