^You're definitely right to be cautious, but you also need to do your research and not let sensationalism dictate how you are going to deal with your problems. Methadone, like all powerful Opioid agonists, can kill and needs to be treated with respect, but in my opinion, in most instances involving an overdose, it's rarely a "complete coincidence". Usually, a mistake or two is made leading up to the event. This could be a decision to have a few drinks, take a Benzodiazepine etc., but you can't treat overdose like the boogeyman. It's not going to just sneak up on you if you do everything right.
A good metric for how much and when to take in terms of Methadone or any Opioid is going to be how you feel in terms of withdrawal. If you are indeed withdrawing physically from your previous Methadone dosage, it's likely that another (same) dosage can be tolerated no problem. Especially if it's as you say and you're not taking anything else in conjunction with the Methadone.
From here, I would recommend getting a good "baseline" with your Methadone. It works differently than Oxycodone in terms of its onset time and duration of action. Find out exactly how much is required for you to maintain yourself and for how long, then, mover forward with a taper.
A very important piece of information regarding the onset of action with Methadone, is that 3 hours is commonly cited as a "safe to redose" point, but in my experience, depending on stomach content and other variables, it can be as long as 5 hours before I experience the peak of effects.