Default [q] tethering usage amount

Longtime customer of TMobile and really fed up with the entire data issue. I still can't believe they were able to get away with the "unlimited" throttle back which was worthless when it happen. I admit to a little resentment.. Anyhow I digress. My current plan allows for unlimited data on my phone and 6.5GB Hotspot (tethering). I do not listen to music, or watch videos on my laptop the device being used for mobile hot spot. However last few months I max out. This month I received a text on the 4th I had used 6 and less the an hour later another text used 6.5, so I bought up to the 8 and 3 days later received text saying I had used the 8. Its not possible I am only sending emails and simple web browsing on laptop. ALL DOWNLOADS, software, music, videos, etc are being done on my phone. I went round and round with TMobile and all they can tell me is the total amount used. How can I tell amount being used on laptop?? And if the CSR at Tmobile cannot give me those amounts individually am I suppose to blindly trust them? I DON"T. Something is not right here.. can anyone give me any suggestions or advice?