If you say that its a small setup and u dont have a network admin and stuff , then i doubt it is port blocked....i had this discussion once with my network admin and work and he had told me that everything can be controlled via the router console and 'something' which i don't quite remember.....in your case it might be the multiple routes that your network must be taking or it must be just capped by your ISP itself......check a usual download and see what download speed u get over HTTP / FTP.
Also , there are various programs that claim that they will increase bandwidth and stuff , but then at the end of the day all they will do is get more and more of spywares and adwares on ur system........