Why not let your wife fuck you for a while. Promise yourself you will only use 2/3 of your dick on your own. Then she will reach for the rest when she feels she wants it. She’ll probably notice as she tents that she wants to be more filled and will push out or sit down for more. Her cervix will slip up and out of the way. Watch for the signs and timing of when she does this so you can anticipate better later. Eventually, she may push for every millimeter. Then pound her into another dimension. If you still reach the CDS fireworks. Right now you may just be training her to expect pain and to be less free with her motions.