I keep going round and round this one the same as you. Even with professional help it damned hard. I've had enough success at times to suggest the following order of exercises : in your situation it will probably take you several months to make progress.

So the order of core exercises is:

1. Abdominals
2. Gluteals
3. Hip Rotators

I will write out my physio notes for these 3 levels (pictures would help I know)

1. Abs: Lie on back with legs bent and feet together. Tilt pelvis to find the middle position (spine neutral). Pull up your pelvic floor muscles as hard as you can, feel your tummy muslces move inwards. Aim repeat 10 times hold for 10 secs. Once this is easy add in a leg slide and then a leg drop to side.
2. Gluts: Lie face down with your hips and back relaxed. Pull the stomach up and in, and gently squeeze both buttocks and flatten the low back. Build up to 20 secs.
3. Hip: Lie on side with knees bent. Hollow the stomach as 1. Leave heels together slowly lift the top knee by turning the hip out without letting the back and pelvic tilt.

Thats your aim: if you can do these 3 you're nearly cured. Easier said than done though.