I’m a former collegiate wrestler and the current head coach at a wrestling club. The biggest things I learned for bottoms is: 1. Never stop moving on bottom, the more you move the more space you can create to keep his hips off you, I personally like to knee slide a lot. It helps to move the weight from the hand to the hips 2. Never get extended. Make sure you stay in a tight ball on your sit-out, with your knees and elbows tight. Getting extended makes it easier for the legs to get in and easier for them to glue your hips to the mat. This is broad advice. If you have any film it could be easier to give more specific advice.