Hip issues?

I am training myself to do middle splits.when I try to go down lately my legs move behind me and I end up out of the stretch. I do the frog stretch and am pretty good at that now. The squat where you open your legs into a straight line. Got that. The forward bend. Progressing nicely. Butterfly stretch. piece of cake.But when it comes to the straddle...I suck. I have been doing the wall straddle for a month and a half by now..maybe longer..and I am not progressing ? It's the same semi wide v and that's with me pulling my legs down. Literally no progress. no little by little anything. I'm thinking about getting ankles weights for that.. I also sit and push my legs against the wall to open my legs. Same semi wide v. I push myself with these stretches twice a day . I do it for long periods of time. I can't open my legs that wide by myself either. It's a plain v if I try to open my legs without pushing against something. What the heck am I doing wrong.. I seem to be progressing in my other Stretches.