Good morning. Sorry for the delay. I saw your response this morning when I got up.
Your medical situation looks very complex. However, reading through everything you wrote, I am inclined to ask why you are not taking a diuretic on a regular basis.
There are 2 common causes for edema as you describe. One is congestive heart failure, the other is a compromised vascular system. In your case, from your description this would be venous insufficiency, or venous stasis. This happens when the internal structure of the vein is damaged. There are normally, what you might call "one-way check valves" in the veins which keep the blood flowing in the correct direction (toward the heart). When these are damaged, or no longer working properly, the blood can slow down enough that fluid leaks from the blood vessels into surrounding tissues----which causes the edema or swelling.
The treatment for this is diuretics (more than a low dose "as needed"), leg elevation, with some walking in between to help the blood flow (muscle action), and compression with specially made stockings.
You would need a doctor's approval for the compression stockings, however. If you also have impaired arterial circulation, this would not be appropriate because it would cause a lack of oxygen to your tissues.
You have the correct idea about leg elevation, but with your swelling it would have to be almost constant. If you have a recliner chair, you can also add a fat seat cushion (like the size that comes off of most couches) to the elevated foot rest. Also, at night if you use a fat cushion to prop your feet and lower legs (ankle to under knee) and allow heels to dangle a bit (prevents pressure and skin breakdown), this would reduce the swelling so that you can put compression stockings on first thing in the morning (if your doctor approves), and before you get up, and the swelling starts getting worse.
Something else to consider is diet. You need to have no more than 1500mg of sodium in your diet daily. If you have not yet drastically reduced the amount of sodium you eat, this might help quite a bit. This requires some effort. You have to keep track of all the sodium you have ingested for the day. And need to read labels and pay attention to serving sizes. But it would be worth the effort.
The pain you are describing in your feet is from the pressure put on your tissues with the shoes you were wearing. You must be careful with footwear, since edematous tissues can be damaged very easily, and you could end up with pressure ulcers.
You need to check with your doctor about the reasoning for low dose Lasix before you increase the dose. Your doctor may know of a reason why you cannot take a larger dose.