Find you a small outdoor antenna and set it up on your balcony. That Winegard is not much more than a wire loop antenna, anything with 8 or 10 elements will blow it away at the same position.
From the picture , it looks like you are on the SSE facing side of the building, while the stations you desire are to the SW, that makes the apartment building an obstacle to reception, but by taping the Winegard to the wall of the balcony you may have caught just enough of the signal parallel to the wall.
Further research shoes that 21. and 41. are located on a line parallel with the south wall of the apartment building, but I am still surprised that you were able to get 2.1 since it is not the strongest signal that it could be (50.9Kw ERP), whereas 4.1 is at 1000KW ERP, perhaps 2.1 has upgraded their transmitter or antenna and it does not yet reflect in the FCC database.
Can you mount a yagi style antenna on an "L" shaped pole protruding out from your balcony to give you better LOS to the transmitters?