Hi MyBackIsKillingME and welcome to The Mattress Underground 
Glad to have you here.
Sorry to hear about your problems with your less than 2 year old mattress. Each mattress is unique to the sleepers using it, and is based on your stats (height, BMI, sleeping position(s)and any underlying health conditions) and the sleepers’ PPP (Posture and alignment, Pressure relief, and Personal preferences). Thanks for providing your stats, You both have lower BMI’s but you have found the major drawback to ‘big brand’ mattresses…Leesa, like many big box retailers, is not transparent about the materials or thicknesses of their components. I took a look at the Leesa site and your hybrid is multiple layers of memory foam of unknown thickness and density. Inexpensive memory foam can ‘break down’ prematurely causing ‘divots’ or ‘ruts’ and it sounds like you are becoming painfully familiar with these. Memory foam also tends to sleep ‘hot’ so this mattress is no longer suiting you as it did when new. It does sound like a painful sleeping experience. You may want to take a look at our mattress shopping tutorial here as well as the [ url=Mattress durability guidelines ... how long will a mattress last - The Mattress Underground]mattress durability guidelines/url] to see how different materials hold up over time.
A Talalay mattress sounds like a good choice. Talalay has a ‘bouncier’ feel than Dunlop latex, which ‘cradles’ more and should be much more supportive for your side sleeping positions. Any Talalay mattress of similar ILD (Identation load deflection) should have a similar feel. I would try different configurations and comfort levels in person if possible. As far as using the Leesa adjustable base, you would need to ask the manufacturer of any mattress you are considering they usually have some firm rules on what sort of base you can use so that you don’t void any warranty. Also, the 10 vs 15 inch question is one only you and your partner can answer, you can have multiple layers of latex of various firmnesses to customize your sleep experience, but it is based on personal choice, within the constraints of the manufacturer warranty of course. Also, an organic mattress topper made of cotton, coconut coir or wool could help regulate heat, as would innerspring coils. It might take a little trial and error but I am sure you can get a mattress much more suitable to you both.
I would suggest taking a look at the Trusted Members of the site; Member Texas Mattress Makers are located in Houston, and they are experienced in matching consumers with the perfect mattress and are fully transparent about their materials and construction, and have excellent customer service. If you are considering online purchases, many of our members have offerings similar to what you are looking for.
I wish you success in finding a more comfortable sleep solution!
Basilio