Help with 3 yr old behavior

Hi everyone! I have a 3 yr old he will be 4 in October. I am unfortunately so drained by him and I think sadly everyone is too. He's a wonderful child, sweet, smart , and caring and just full of life. I love it, he's made my life better. I couldn't ask for life any other way. Only thing I struggle with , what his dad struggles with and my family when they help watch him is that he is very very hyper and likes to push boundaries a lot (he is my first child so I'm unsure what's normal) from the second he wakes up he is just full of energy , he likes to bounce around, and push himself hard into peoples body's , he doesn't understand or doesn't like to listen when u tell him please stop it hurts , he gets extremely loud like screeching almost it'll hurt ur ears, he is obsessed with train tracks and refuses to talk about anything else or play with anything else or watch anything else for more than 5 mins . He has tantrums bad, he'll spit , throw toys , he's hit my dog before. He goes out daily, parks , walks , bike riding etc we play with him a lot , read to him , draw with him. He's in preschool (he is on summer break now) for discipline he gets timeouts , stuff taken away I get to his level and talk to him and explain In small sentences why things are getting taken away. I don't know what I am doing wrong. He was tested for autism and was not diagnosed. He has a social and emotional delay which is why he is in preschool. But I am so unsure on what else to do , I feel like I'm failing as a parent and I'm stuck. Any advice would be so helpful ):