Hey Krisp

sometimes a posterior baby favors that position due to the natural tilt of your pelvis.

you could try some simple yoga poses that facilitate the opening of the pelvis and encouraging the baby to rotate into the more comfortable anterior position
1. sitting on a chair, facing towards the back with the legs wide, mimicks the action of a squat...this can also be achieved sitting on a birth ball
2. kneeling on all 4s, step the right leg forward to the outside of the right hand...so you are in a supported forward lunge position...repeat with the left leg
3. sitting back on your heels, big toes together and knees wide...keeping your buttocks on your heels stretch forward with the chest and spine bringing the forearms to the ground

all of these poses help to relieve pressure on the sacrum, alleviating lower back discomfort
avoid sitting back on the couch as this has the tendency to shorten the pelvic cavity, encouraging a posterior position

hope this helps

Ive got a couple more poses up my sleeve that will help if your interested

xx yogababy