When Ewan was 3 months old, if I didn't feed him at two hours on the dot, I would feel way too full. Now, he's 8 months and I can tell my volume of milk is so much lower.
I had issues early on with over-abundant milk volume and over-active let-down. Both of those are actually very common. Ewan would make all sorts of noises while eating--squeaking and gasping--just trying to handle the milk flowing into his mouth and breathing at the same time. Also, I would always see milk shooting out of my nipple during let-down, if Ewan let go. I still have that problem.
I learned some strategies to deal with these issues from Gini Baker, IBCLC, who teaches at UC San Diego. Let the baby suck to stimulate the let-down, then when you feel it coming on, break the latch and press your hand over your nipple to slow the flow down. Direct pressure will slow or stop the flow of milk. You just want to slow it down, so do it for about 5-10 seconds. Then give it back to the baby. This will help.
Also, beastfeed in a laid-back position. This will make the milk run up-hill and slow it down, too. I regularly do this, especially at 5am when Ewan wakes up and bring him to bed with me. I stack the pillows up behind me and lean back with him in a cradle position. We will sleep like that until he won't sleep anymore.
I first noticed that my milk volume was lower about a week ago. It also seems to take longer for a let-down to occur sometimes. I don't think anything is wrong. I'm pretty sure it is happening because Ewan is eating solid food and nursing less during the night. He's been doing better about sleeping from 8pm to 5am without needing me.
I had this same feeling when I wrote this post back in September of last year. My milk supply was going down from being too high, and I was worried, but what I was experiencing was totally normal.
My doula told me when Ewan was about 2 weeks old that when he started eating solid food to watch out for the return of my period, because he will be drinking less milk. Your period comes back when prolactin levels get lower. I've really enjoyed not having a period since September of 2009 when I got pregnant. It's been about 18 months. I barely remember what it's like to have one!