Calculating due date when cycles are different each month?

[faithfulbird]

Particularly due to taking vitamins and also having a miscarriage...my cycles are a different length every month. But my average is coming out to be 27 days...

Due date is based on the first day of your last period and to be as accurate as you can I'd work out the average cycle length out of the last few cycle lengths (as many as you have recorded the better)

But due date will never be very accurate until your dating scan at 12 weeks (and even then you could give birth weeks before or after lol)

Oh sorry I don't know how I missed that you already worked out the average 🤦🏼‍♀️ lol I'd use that but expect it to change loads at your dating scan. Sometimes they change your due date by quite a lot x

Not sure you can do much else, except notice other signs e.g. cervical mucus, aching/pinchy feelings (when you think you might have ovulated)