So hard to tell if my son is starving or cluster feeding

Maria • Mommy to 2 girls💕& a baby boy 💙

So I've been breast & bottle feeding (pumping during or right after the bottle feeds and/or every 2hrs) and it's because my supply has been very low from the beginning & my son wasn't gaining. Yesterday, the most exciting thing happened..I actually for the first time ever heard my son gulping as he was nursing..and also for the first time he unlatched himself and stayed content. I wanted to cry tears of joy. I thought omg this is it..I'm finally making a good amount of milk for him. So I decided I'd try not supplementing from here on out and just exclusively nurse him..no more bottles, how I've wanted to do it from the beginning. Well last night was the worst night by far..he literally never seemed content..not once..but I wanted to keep trying to stick it out. He didn't go to sleep until 3am, after I caved & made a damn formula bottle. He literally was WIDE awake & fussy from about 7pm until 3...i didn't even think a 3 week old could stay awake for 8 hours straight!? Then he's done the same thing all day so far..isn't content enough to sleep & has been awake since about 5:30. It pisses me off that my body won't just do what it needs to. I mean..is this cluster feeding, or is my supply not where it needs to be yet & he's starving!? I'm so jealous of the women who have been nursing from the start without any issues..😕 I really thought my body was finally getting somewhere.