Noob BC muscle question(s)


I’m posting because I’m a little confused and the searched topics didn’t yeild definitive answers to my q’s.

I basically got done ejaculating a few hours ago. My g/f and I had been going about 80 mins or so and I pulled out to come on her stomach.
I read a few days ago about pushing instead of allowing the PC to clench and by doing this using the BC muscle. So I used my BC muscle by “pushing” when I needed to come. (If this is incorrect please let me know because I thought this was the difference)

I held the push for about 5 seconds but I couldnt hold much longer and began to have pc “contractions” like a regular ejaculation.
Before I did this I noticed I was sort of ‘pee-ing’ semen. It was very white, not mixed with precum like I usually get (Translucent and white areas)
Then when I resumed a regular orgasm all I got was precum. Well at least it was mostly translucent.

Can anyone explain what BC muscle contracting and ‘pushing’ does? I was under the assumption that you could push through an orgasm. Would this enable you to carry on while still aroused?

In terms of Multiple orgasms:
I am able to carry on by inducing orgasms (clenching the PC muscle and holding while stroking or pumping [fast]), the most I’ve managed is 4, but then I lose any sort of arousal, and continuing is completely unarousing.

Thanks for any help.