Can you describe your actions step by step?
it was a while ago so i'll try to remember. first i went to the beach, because i wanted to ctb there. I sat by the side of the beach, where it was kind of shallow, and my feet were in the water, just barely. i enjoyed the scenery then i tried it. I sat in the water, where it was deep enough for my head to go fully under. i hyperventilated for a bit while curled up in a ball, after i think about 2-3 minutes when i felt it was enough, i quickly stood up and held my breath, in about a second i passed out. i remember the feeling of my face hitting the cold water and instantly being woken up. i tried this several times, again and again, until i gave up. i got extra desperate so i went into the pool. i would like to add, it was the middle of a cold night, it was super super cold. hypothermia isn't for the faint of heart. in the deep end of the pool, there's a tiny ledge about a foot down from the water line where you can sit. i sat on there and hyperventilated, did the same thing. again it didn't work. every time i would hit the water, it would make me snap back awake and survival instinct would kick in, and i would try to swim. shallow water blackout makes you pass out, but it's not a deep enough state of unconsciousness to keep away survival instinct. your body is still very much functioning, it's just your brain passes out for a few second. and i also did this before the water. a lot of times i practiced passing out with this method on my bed or something, and i would be able to stay unconscious for at the most a minute. your best luck is if when you pass out, you sharply hit a rock or something, and you end up passing out that way.
probably a dumb method, but if your really desperate you could do it in water, next to a big sharp boulder or something, and position yourself so when you fall after hyperventilating, you hopefully hit the rock. pretty dumb though if you ask me a lot could go wrong.
this method just simply doesn't keep you in a deep enough state of unconsciousness. so if your planning on doing an unconscious drowning (my preferred method), use something like a gas (like N2O) or a very strong drug. it'll keep you unconscious enough to drown (if it's strong enough)