riding him good

So my new boyfriend that I've been dating sence October of 2016 I can't ride him without feeling like I'm doing something wrong I get into my head and don't think I'm doing it right with my boyfriend I had before him I was his first and I could do it no problem I dated him for 2 years and he had a big dick to the new one isn't as big but it does the job he love to be road but I can't do it someone please give me some tips