Accepted answer
3 days past a due dose is 0.43 half-lives at the seven-day half-life this class runs on, which leaves about 74.3 per cent of that dose still circulating. One line of arithmetic: remaining fraction is one half raised to days over half-life, so 0.5^(3÷7) = 0.743. At 74.3 per cent you have not been off it in any meaningful sense. The interval stretched from 7 days to 10 and the trough went lower than usual; that is the whole of what happened. What the product label says and what the pharmacokinetics say are two different answers here, and the first is the one that governs. Restarting, holding or stepping down after a gap is decided under supervision, and nothing here is medical advice.
Start with the interval since the missed dose, because that single number determines the answer.
To change your regular dosing day, move the next dose later rather than earlier, keeping at least three days between doses for a weekly agent. Moving earlier compresses the interval and raises exposure.
It helps to be literal here: with a one-week half-life dosed weekly, missing one dose means exposure falls by about half over the following week — the same trough you would reach if you simply extended the interval. That is well within the range the agent operates in.
Peak exposure rather than average exposure drives gastrointestinal tolerability, which is the reason doubling up is advised against.
Never double up. Peak exposure is what drives the symptoms.