"expected" period on 19/10, still do not have it, hpt result (-) this morning. Could it still be a bit too early or am I overthinking things?

See below. If expected period was on october 19 and hpt negative this morning; assuming you did the test correctly, you are not likely to be pregnant. See this site for other causes of missed periods and discuss the matter with your doctor. http://women.webmd.com/tc/missed-or-irregular-periods-topic-overview.