Is 1500cc of pure fat removed from lipo enough to make a difference?

Not even close!  1500 cc might be enough to remove from an average person the arms.  From the inner thighs and knees and arms you should have seen 3 to 4 times that much, unless you are less than 100 lbs or didn't really need lipo.

the amount removed is not as important as the end goal and the type of procedure.  my hi def procedures almost always remove 5L and get very significant improvement (see my IG).  however, if you are large 1500 is very small and if you are small 1500 maybe a lot.  I suggest seeing an expert.  Best, Dr. Emer.

The amount of fat you need to remove to make a noticeable difference depends on your weight and which areas you had treated. Inner thighs, knees and upper arms are all relatively small areas, so 1500ml of fat would be quite a bit. If your BMI is anywhere under 35, I would expect you will see a definite difference once your swelling goes down. If your BMI is higher than this, you may not see as much of a result.

The amount of fat one needs to take out in a certain area to make a difference depends on the size of the person and the area they are liposuctioning. For example, 50cc removed may not show in the abdomen, but can make a difference in the neck. While you heal from the procedure, you may have some significant swelling which can also make you feel like you didn't have enough removed. You should wait until you are fully healed to better judge the final results.

The only measure of whether enough fat was removed is the way you look afterward. That's all that matters, so if there's a lot left behind then perhaps it wasn't enough.