I suggest you forget about that female and use a different one. She sounds stressed and that may take a couple of weeks to fix. Isolate her, no exercise, just feed to condition and keep up with water changes. After a few days, flare her to a different color of the male, preferably a smaller female. If she flares, exercise regularly for a few days. Then try flaring to the same color as the male. Also do this for a few days. Let her gain full confidence. She should be in breeding mode by this time - she should flirt swim when ever she sees another betta.
Set up the breeding tank and everything. Use extra hideouts. Since she had been stressed, I suggest immediately releasing her just before dark ( she might become stressed again if floated too long). Keep an eye on her for the first half hour. Make sure she is flirting with the male. At night, without extra light, they should become inactive but can sense each other. Hopefully she will spawn the following morning.