Hi merup,
I would agree with BB and I would also add that I think all three layers are much softer than I would consider using at your weight. This would be a very risky construction for you both in terms of durability and in terms of alignment and support. It seems way too soft to me for your higher weight.
You can read a little more of my thoughts in post #15 here about trying to design and build a mattress completely on your own without the guidance of an “expert” (or in many cases the exchange or refund options they make available) using components your purchase individually. In most cases I wouldn’t recommend it unless you are prepared for the time and effort and the difficulties and frustrations that can be involved in research, testing layering combinations at local stores, the possible cost of mistakes (in money and possibly sleep quality), and a very steep learning curve.
You can read more about the differences between a latex hybrid and an all latex mattress in post #2 here. In your case, because of your heavier weight you will likely “go through” the top layer and well into the middle transition layer which means that the quality/durability of this layer would also be very important to you.
You can read more about the many factors involved in the durability of a mattress in post #4 here and the posts it links to.
Post #2 here and post #5 here may also help you with the parts of a mattress purchase that are most important.
The first part of post #2 here has some information on accommodating significant weight differences or different needs and preferences of a couple that will be sharing a mattress.
The first place I would start though is post #1 here which has or links to the basic information, steps, and guidelines that are the most important parts of making the best choices.
Phoenix