Need help on how to achieve a rhythm in my fighting and on bag work

Whenever I watch back footage of me hitting the bag, I can see that I’m too jumpy and excited, along with tense in shoulders. Can anybody put into an explanation on how I can get a calm sort of rhythm to my fighting, is there a sequence of pattern like 1,2,34,1,2,3,4 etc that I could use mentally. And also some advice on how to relax my shoulders more whilst still having a strong guard up. let me know if u want footage to better understand what I mean of my lack of rhythm.