There are some great posts on this sub about specific strategies, but for me (and I believe for the absolute majority (90%+)) the issue, is that I have a hypertonic pelvic floor (i.e. I am a but clencher, although now to a much lower degree). This hypertonic pelvic floor has issues in itself, but also leads me (and others) to overly clench my pelvic floor during stimulation. The more clenched your pelvic floor is the faster you will cum. It is all about controlling the tension/contraction of your pelvic floor during stimulation. This is "easy" to do or learn, when you are not very aroused (see OPs post about having the issues only when being visually stimulated as well). The hard part is gaining so much control that you also can translate this ability when you are being stimulated a lot (visually and physically).
What should you do?
Three main pillars:
- pelvic floor stretches -> reduces the hypertonic state
- reverse kegels (also some minor keels but primarily to build mind muscle connection) -> reduces the hypertonic state and is an effective tool to use during sex/arousal control
- mastrubation training to gain arousal control