Re: decrease in milk supply or growth spurt?
There are lots of options that could explain what you're experiencing. This could be the big growth spurt that hits around 3 months- if you hadn't mentioned getting your period I would have said that it was almost certain to be the spurt! It could also be teething- many babies begin to teethe around 3 months though the teeth may not break through the gums for many months to come. It could also be related to your period- many moms notice a drop in supply around the time their periods return. Provided you just roll with he frequent demand, there is absolutely no reason to think you will need to supplement. The best way to increase supply is always to simply nurse, nurse, nurse... And then nurse some more!
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"