I normally avoid making specific speech therapy technique suggestions, as I believe that programs are effective. Programs include techniques, but the techniques themselves don't yield lasting results unless part of a program. BUT, seeing as you have a special circumstance... With your P's and B's.... Don't close your mouth. Keep your lips apart. Outward mouth breath through those sounds. Practice "peanut butter" as being close to "eanut utter." Go slow. It's really difficult to describe without demonstrating. Eventually you want to get close to closing your lips for the P and B sounds, but never close them. Keep the air coming out as you pass by those sounds. But when you start practicing, start with completely bypassing those sounds. As you get comfortable with bypassing those sounds, you can try coming closer to making the P and B sounds, but still avoiding closing your lips. The reason you want to avoid closing your lips is that it stops the airflow. If you can maintain your outward airflow, it may help your fluency.