Seeking experts advice for latex mattress firmness and layers

I am not sure if this should fit better in another category to attract some attention but here it goes. I will try to give as much info as possible and pray its enough. I am 1.94cm tall (6’4) and 110-115 kg (240-250lbs, my weight bounces around those numbers). I always lay on bed on my side and end up sleeping in my back. Now that that info is out there i will try to explain my issue. I didnt go through the rabbit hole of reviews and comparing mattress, even though i spend couple days on settling on which company/manufacturer i should choose based on their certifications. After that i found the stores they supply and spend the last few days testing them. They mostly have available solid blocks of latex without the DYI layers i see people build around here so i could only test specific things. The latex on all the mattresses im gonna list below is from VitaTalalay. I tried : 1) extra firm 20cm 2)firm 20cm 3)medium 20cm 4) medium soft 20-23cm and some combination of coconut coir with latex that i will exclude since it seems pointless to me. The best advice people give is usually ‘‘try them out’’ and while i did try them out i am such an uneducated person when it comes to how my body should be on the mattress that i cannot tell which one is for me. At this point i wanna mention that while being 110kg(240lbs) the majority of my weight starts from my waist and ends above my knees so tldr heavy/fat glutes and upper legs. The extra firm mattress felt nice, no sinking, floating on the bed instead of being inside but i am not aware yet if thats good or bad. The firm almost the same feeling with a noticable difference. The medium/medium-soft allowed my butt to sink in, which again i am not aware if its good or bad( felt good at the moment). The issue here is that when my glutes sink in it creates that downward motion that makes my torso/upper part of the body to almost feel like its lifting from the bed and going into the sitting on a chair position. You can argue that the extra firm/firm while not letting my glutes sink in, it also doesnt allow my shoulders to sink in. The bottom line is, before i go out there again and again to test the same mattresses or even order a DYI latex bed(i live in Greece/Europe btw), i really need some advice on HOW i should feel. Sounds like a dumb question but i am clueless on spotting when something is good or proper for my posture since i come from a very bad foam mattress.

@Arizona_Premium
@Sleep_EZ