So if fuel prices and the amount of useful heat usage stayed the same, then your bill should be 1.03/1.25≈82% of what it was before. If your bill is "less than half" then something else must have changed.
Any modern boiler (gas or oil) will almost certainly be cold start, so it only fires when there's a call for heat. This alone probably saves a gallon of oil a day at least.
It's really hard to predict where prices are going to be in a year, because you really have to predict how well the oil industry can predict future demand in this environment. If they shut down too much production and then demand comes back there could be a price spike. If they expect a quick recovery and are wrong, prices could remain on the floor for a good while.
According to the NH page, that price was June 2. For the Commonwealth of MA, as of late May it was $2.07 on average and it's down 33% on last year:
https://www.mass.gov/service-details/massachusetts-retail-he...
You can see it has dropped from $3.04 on Jan 7 2020.