Thanks everyone for the information. This will help me to ask better questions. Now I just have to wait about a month because the company I called is backlogged four weeks. Good news for them, bad news for me.
I could get you the return sizes in the basement, I know it changes sizes (small to bigger) a few times, but I have no idea what is in the walls.
I also guess one thing I could try is to close all the duct dampers to the whole house except maybe two of the rooms that are on the far end of the house to see how much more airflow I can feel. Granted, I don't have a device to measure airflow coming out of those supply vents, but I could see if the air flow increases.
This is just really frustrating (especially if I have to buy a whole new compressor to size it correctly). If that is the case though, what options do I have? I can't go back to the builder, so can I just add a second compressor to the system to piggy back on the first?
If the compressor is not undersized, couldn't I just add a new blower that has larger capacity or could this cause issues? Such as what?
I'm just looking for ideas. I do know that the air temp on the supply vents close to the furnace are quite cold, so I would think the size is right. I think I understand the duct (supply and return) size theory (too small on the return and it may starve the system). If it was air starved though (and the blower is the right size) I would think the return vents would be really noisy and suck paper to them quite easily. When I place a piece a paper on my returns now, it just falls off. I can feel air moving by my hand when I place it near it though.