Hi angiebullock,
Welcome to the site … and I’m glad you found us 
You’ve probably seen this already but there is more about the Purple mattress and the buckling column gel they use in post #2 here.
While it sounds like your Leesa mattress may be a little to firm for you … I would also keep in mind that there will be a break in and adjustment period for any new mattress or sleeping system as the mattress loses any of it’s “false firmness” and the cover stretches and loosens a little and the materials settle and your body gets used to a sleeping surface that is different from what it is used to (see post #3 here). This could typically be a few weeks but it can be shorter or longer depending on the specifics of the person and the mattress (higher density materials can take longer) and it can be surprising to many people how much their sleeping experience can change over the course of the first month or so. Unless your “symptoms” are too severe and/or it’s obvious that it wouldn’t make any difference … I would generally suggest sleeping on any new mattress for a few weeks at a minimum before deciding whether to keep it.
If you prefer an “in the mattress” feel then you may either prefer a mattress that has memory foam top layers which has the typical slow response and more “in the mattress” feel of memory foam (unlike the Leesa) or if you choose a mattress that has more resilient materials in the top layers like polyfoam or latex then you may prefer a mattress that has thicker/softer top layers and is in a softer firmness range.
I would keep in mind that there are 3 main types of “foam” (memory foam, polyfoam, latex foam) that all have very different properties from each other so I would be very cautious to make sure you know the type of foam that is in any mattress you are considering. Layers that are closer to the sleeping surface will have a bigger effect on what you “feel” when you sleep on a mattress than layers that are deeper in the mattress.
Again you may have read this already but there are some comments about the Luxisleep mattress in post #10 here. It uses good quality materials and there are no lower quality materials or “weak links” that would compromise the durability or useful life of the mattress relative to more average weight ranges but as you probably know it’s not a memory foam mattress.
The Novosbed mattresses and the Dreamfoam mattresses you mentioned are memory foam mattresses in the same general category as the Tempurpedic mattresses you tried (see this article). They are both members of this site which means that I think highly of them and that I believe that they compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency. There are also no lower quality materials or weak links in either of them that would compromise the durability or useful life of their mattresses relative to more average weight ranges.
Subject to first confirming that any retailer or manufacturer on the list that you wish to visit is completely transparent (see this article) and to making sure that any mattress you are considering meets the quality/value guidelines here … the better options or possibilities I’m aware of in and around the Houston area are listed in post #2 here.
Any specific mattress may be the “best” match for a relatively small percentage of people, a “good” match for a larger percentage, and an “OK” match for a larger percentage yet but the only way to know for certain whether the mattress you end up choosing will be a “good enough” match for you to keep it (even if it isn’t the “best match” out of all the mattresses that you “could have tried” instead) will be based on careful testing and/or your own personal experience when you sleep on it.
One of the advantages of trying mattresses locally is that you can try many different types and styles and firmness levels and compare them to each other in “real time” based on your actual experience rather than just “theory” instead of trying one mattress and not knowing how it compares to the other mattresses that you could have tried or purchased instead.
Of course many online mattresses have a good trial period and return policy so you can try them in your bedroom instead of a showroom with little risk (outside of the time you spend sleeping on it and/or returning it if that becomes necessary or any costs involved in the return process) so if it’s not a “good enough” match for you you can just return it and try another mattress although of course you won’t know whether it would have been better or worse or how it compares to other mattresses that you could have tried that you haven’t tried in person.
In both cases it’s really a matter of risk management and “tilting” the odds of success in your favor as much as possible.
I’m looking forward to finding out what you end up deciding … and of course to any other comments or questions you may have along the way.
Phoenix