Do you have emotional breakdowns since becoming a parent? Especially a first time mom?

My 2.5 months old baby is exclusively breastfed, and since 2 or 3 weeks ago I've been worrying about if my son is getting enough. He started being distracted, and at some feedings he would take only 8 minutes on 1 breast and that's it.

I have a scale and I weigh him before and after each feed. For the past 2 days he also wasn't eating a lot, some feedings he only takes 2.5-3.5 oz, whereas on good days he would take between 3-7 oz per feeding.

Today got worse - I think he got 1 oz at the 4pm feeding and maybe 2-3 oz at the 7pm feeding. And at the 7pm feeding, I don't know what got into me and I felt that I was losing my milk supply because after my breasts felt softened, my baby is still latched but he wasn't sucking (or sucked very lightly). He usually wouldn't even take my breast if he's not hungry (I know some babies hung onto the boobs for comfort but mine certainly don't). People say that when they suck and nothing comes out they would give up sucking and I thought that's what's happening. So frantically I went to the fridge and get the expressed milk to feed him but I wasn't sure if it was because I acted like a crazy woman so he didn't drink much, or was he simply not hungry. I also panicked and pumped 15 minutes after the feed which I kinda regret now.

His weight is still in the 75-90% but his length has dropped to 50% (used to be in the 75-90% also). He has been stuck in the same weight for the past few days if not a week or more.

Is this normal or Am I the only crazy one? do you guys have breakdowns too? I feel like I am losing my mind. I need someone to tell me it is OK but when they do tell me that I don't believe them. I am just worried how am I going to go on when there are so many other things I need to worry about down the road...