You need to get the antenna outside and up high. Putting an antenna inside a structure is going to severely limit it's performance.
Inside your home you have electrical wiring, plumbing, metal heating ducts, foil backed insulation/vapor barrier, metal appliances, etc. All those things will absorb or block RF energy.
The "1000 watt" antenna doesn't really mean anything. It's the manufacturers way of trying to talk up the product. Your CB is still only running 3 watts.
Echo mics won't really improve range. They will boost audio, which can increase modulation levels and audio, but that won't increase the power of your radio, except by increasing the modulation levels. If you crank them up too high, you can actually distort your audio bad enough to make it unintelligible.
I understand you may be unable to get the antenna outdoors. That's going to severely limit what you can do. The best you can do is put the antenna as close to a window as you can, or if possible, out on a balcony.
Other thing you could try, which may not be permitted by the owner, would be to try a wire antenna. Usually they are low profile enough they go unnoticed. Building a simple wire dipole antenna cut to work on the CB band and getting it outside will likely help. Problem is you may still upset the landlord.
If you really want to talk to someone, maybe this might be a good time to get into amateur radio. You can use higher frequencies, like 2 meter VHF or 70 centimeter UHF. Those use much smaller antennas. Utilizing the repeaters that are out there, you can easily talk over a very wide area. In Windsor, you shouldn't have any problem finding others to talk to on the amateur bands.
Check around and see if there is a local amateur radio club you can talk to. Some of them will do licensing classes and help with the training. Might be a better option in your case than the CB.