Question, when you are using your personal computer and experience a slow down. Are you connecting through WiFi? Are you unable to stream when directly connected to the modem? Based off of your diagnostics, I am not seeing anything yet, out of the ordinary. However I think some more tests will need to be done to confirm this.
At this time speed tests of the connection speed being beamed down to your dish are:
Your speed tests are exactly in range. They will fluctuate, however as long as they do not stay low for an extended period, you should be fine. With those speeds, you should be able to stream at some of the higher end settings. Although to conserve data, standard or lower is best. Have you noticed a difference since seeing these speeds. Didn't see you mention trying to stream while directly connected to the modem.
Anything in the 13-20+ Mbps range is very good IMO. Plus that first page of tests is one right after the other during peak time. Is suggested to at least space them out a bit. My results are wonky if I do one test right after the other.
Also, to conserve data, run 15 MB manual tests as if speed is really good the 12 MB test will often bump up to a ridiculously high test amount.