Well given your current training volume that makes sense. You are not getting any time to recover.
The first thing you need to do is take a short break. 3-5 days of quality eating and rest. Second - I would ask you to prioritize the 3 goals you have outlined.
1 - Leaner
2 - Faster
3 - Stronger
Of all 3 the one component that is a part of all of them is strength. What are your lifts like? (Bench, DL, Squat, Pull up)
Not knowing you and simply going off a hunch I would look at a split more like:
Mon- Fri am swim 30 minutes
Mon night - heavy lift
tueday night - muay thai/conditioning
wed night - rest
thurs night - heavy lift/light conditioning
fri night - boxing
sat am - strength/conditioning
sat pm - heavy lift
Net:Net - You need to rest more and work on getting your strength numbers up. Once you do that then the leaness magically appears and then you can begin to work on the dynamics of speed.