Here's what I do to troubleshoot speed issues:
1. Check if your route is TW or PIE (TW can become choked more often than not vs PIE, in my experience - not necessarily TW's fault, but just the route the packets may take can be the result of the choke).
2. Do a speedtest. If you think speedtest.net is throttled, go to nperf.com and pick a server either in Singapore, France, the Netherlands, UK, Germany, UAE or if you're bothered, the east coast of the US (not Canada). It'll give you an idea whether the website/route is choked, or whether your connection is saturated. And you'll have hard evidence as well.
3. If you see that the speedtests to different websites are fine (but not to your website), then you can try asking them to change your route from PIE to TW or TW to PIE.
This is how you can narrow down whether it's a Stormfiber issue, a backbone issue, or something else.