I would suggest the Halcyon soft weight pouch. You can place more weight in the lower section.
Extreme Exposure
Or a tail weight pouch from Deep Sea Supply. Tobin makes them in two lengths.
Tail weight Pouch for Doubles, 5lb capacity scuba
Extra Long Tail weight pouch for Doubles, 5lb capacity
There is no reason to use ankle weights.
**You mentioned in an earlier post that your harness is loose.
Make sure it isn't too loose. You may have introduced some changes in an attempt to fix your trim problem, and are now chasing your tail.
Return to zero......get your harness adjusted, properly if it isn't already.
Shoulder straps with approx. 3-finger width of space between you and the shoulder strap. Arch your back when diving.
Then adjust your crotch strap so that it creates a bit of a downward pull on the waist belt, when you close the buckle with the waist belt snug.
Get all of that correct, and then see if you are really having a trim problem.
I have to ask.....Are you really having a floaty feet (feeling like your head down)?
Or do you just "feel" like you are?
Some divers will insist that they are head down, because they "feel" like they are. When shown a picture or video, they are often in trim.
Sometimes it boils down to getting the body awareness, and "knowing" when you are in trim.
You will just get a feel for it.
Try hovering motionless very close to the bottom without touching. Arch your back, and just do nothing. Being close to the bottom will give you some feedback about your trim position.
Are you flat? Knees down? Head down?
Also......being in trim.....arch your back. Exaggerate this at first until you develop the feel.
But, arching your back is important.
Ankle weights are not the solution.
You may be only a few fine tuning steps away from getting yourself dialed in.
If I haven't mentioned it....you should arch your back.
Regarding fin weights....yeah...it makes some difference, but not that much.