Your largest issue is most of the equipment you can buy to do this is in the grey area of being legal. Most has a disclaimer that you must get permission from the cell provider to use it. The cell providers do not want to be bothered with this unless they somehow can make money off it. IE you buy some solution from them.
Even bigger antenna like your dish falls in this catagory. You technically can't use it unless you have a official paperwork from the vendor saying you can.
Because of this not a lot of the larger more reputable companies even make equipment. If you attempt to buy quality equipment from say a manufacture that sells to cell phone companies they will ask you for your license numbers before they even sell you stuff. Kinda why you can't just buy your own cell tower radios, they are not that expensive.
So you are pretty much left in the dark hacking together stuff from vendors you can not be sure are even selling you what they say they are. Things like signal amplifiers are the worst because you have no way to verify the levels the device puts out and even more important how much noise it adds to the signals. The providers mostly ignore this but if you were to cause interference they will complain and the government fines are huge.
The best option to see if you even have a chance of this working is to take the antenna you are using and hook it directly to the router outside. This eliminates the cable loss. If this does not work I doubt there is anything that will help. You may not be using the proper antenna. Most cell antenna are yaggi tuned to the frequency you need or what is called a log periodic