I’ve given up

My baby is 3 months and I have a 9 year old. I work 45-50 hours a week and I have two days off but never in a row. I love my kids and I’m stubborn so I have not had a day to myself since before the baby was born. But today my baby has been so fussy after a night where he was up at 12am 2am 5am then around 7am for the day. It’s almost 8 and he has only slept in the car when we went to the park and one 20 minute stretch. He has been so fussy. I’ve played with him plenty and spent a good deal of the day feeding him. He still isn’t sleeping so I laid him in his cot and stepped away. He’s not crying. I know I’m doing nothing wrong and yes to the mom’s who are going to say this I’m well aware this is the life sometimes of a baby. I’m just venting and getting this out of my head more than I’m coming here to complain as if I had no idea this is how it is sometimes. But when you work and then spend your day off with the type of day I had lol it tends to be a lot because typically a day off is looked at as one to relax etc. I know he will fall asleep soon but I’m mentally drained right now.