Overly stimulated. Stalled progress.

So, I have both books and read this sub often. I also have the Stamena kegal app that I have been using daily. I also have a fleshlight that I practice with. I can generally delay ejaculation now. I am able to see the PONR coming an ease off. However, I still do not feel in control as much as I would like. Soon as I am having sex with my partner I find it difficult to put into practice what i have learned. Its like I become over stimulated and sometimes lose control. I

I cut out all porn but then wondered if it might help if i practiced my breathing / reverse kegals with my fleshlight and porn. To try and get used to the visual stimulation. The problem here is that with some porn I literally feel myself cumming in a matter of seconds! I am unable to do anything.

This all gets me frustrated as I used to be on SSRI for anxiety and could last for ages. Now I feel like a failure sometimes with a few minutes sex with my fiancee at most. i have reached 10 minutes before but that was with constant stopping, changing position, pulling out etc.

Any advice please?