Overstimulation

Does anyone else feel constantly overstimulated by their 3 year old? She turned 3 recently and all she wants to do is cuddle, climb on me, sit on me, she screams during a tantrum and everything is 100mph. She doesn’t play independently anymore and needs us to be near her constantly during the day I also have a 5 month old so it’s tough. Is it just me? I was diagnosed with PND after having my baby but I’m actually thinking it could be overstimulation instead because on days when I’m getting me time, I feel relaxed. Also to add, even after baby was born, she played alone and wasn’t as needy, she’s always had the same attention except when feeding and putting baby to bed. We’ve made a point of keeping things as normal as possible for her.