The WH holds about 6 gallons so I would be concerned if you added enough AF to do the whole TT properly. In one post on here, the OP had a problem with the AF in the WH causing an odd type of anode corrosion that produced white flakes in his WH tank and it was extremely hard to clean out.
It is ok that you left the filter in, just make sure you replace it with a new one in spring.
The low point drains do exactly what they are called, and drain the hot and cold water lines. You would have had to open them and drain out any residue water while you were purging your lines of water prior to you adding AF . If you open these after the AF is in the lines, they will drain all the AF out of the fresh water lines.
If you have any doubts about what you have done you can always re-winterize your TT.
I myself had to do this because the dealer did not winterize my TT properly.
There are many links to TT winterization, step-by-step on here if you need it, or if you look in your FR owners manual they have a page on winterization.
2010 Dodge Ram 1500
2012 Rockwood 2306
DH (Alan), DD (Madison) and Zoey the lab,