I really want to know if Sclerotherapy actually works?

I have done thousands of leg vein injection over the past 30 years .. yes they work!  the doctor of course has to be talented enough to hit the veins..
  generally we see 25 to 50 percent improvement with each treatment assuming your legs are not "covered" with spider veins... a good result can take  an average of 3-5 sessions 2 weeks apart.. but i have seen some patients require 10 or more treatments

It sounds like your doctor is doing the right thing; you really need to have the "root" or "mother veins" treated first. We often don't see these but, if they're not treated, then just injecting the veins you see will result in either no improvement or a complication called matting (new vein formation). Good luck!