Because you have many strong signals, amplification is neither needed nor advised. Amplifiers don't improve the performance of an antenna, they amplify everything that comes from the antenna... desired signals, interfering signals, noise, etc. Driving an amplifier with too much signal power results in a great deal of distortion which reduces the quality of the signal at the tuner. The power levels shown on your TVFR suggest that many amplifiers would be overloaded. Amplifiers have their place... Dealing with losses due to long cable runs and signal splitting. In your case, there is no significant amount of cable and no splitting, so no, I can't suggest any amplification.
WPVI and KJWP are broadcast on real CH-6 & CH-2, which by chance coincides with the virtual channel numbers that you see displayed on screen. WFMZ is broadcast on real CH-45, not 69 as it's virtual channel number may make you think. The problem with WFMZ is likely one of relatively weak signal strength compared to the rest of your signals. The signals on real CH-2 & CH-6 are facing considerably more interference than signal on higher frequencies due to the fact that there is quite a bit more man made RF noise in the Low-VHF (real CH-2 through CH-6) band. In both cases, moving the antenna outside to a location with better signal quality and less noise from electronics and appliances in your home, would be an ideal solution.
Because you're in an apartment, you likely have little if any options for mounting an outdoor antenna... So, stepping up to an antenna with better performance may be one of the few practical options. The question is, are you able and willing to use an outdoor type antenna inside your apartment or on a balcony that you rent? To be effective, you need to find a way to point the antenna toward the west.
Any antenna that has intentional design support for real channels 2 through 6 is going to have what seem like very wide elements. Take a look at the Antennacraft AC9,
http://www.antennacraft.net/Antennas...llChannel.html