Thanks Daniella, that's by far the best solution so far. However its 304 hits from
before:2024-09-11 @Terrypin in:posted
strangely do not include the many before June 2022. I have not yet checked those 304 for duplicates, having seen @zwieblum's post. Nor, I suppose, can I now be sure that the 304 is accurate for that period.
I then tried to work from the earliest month when I believe I posted:
after:2019-05-01 @Terrypin in:posted
but that too reported 304, the earliest again in June 2022.
Then I tried
before:2024-09-11 @Terrypin in:first
which showed two posts in May 2019 and a total of eight (topics I started) before June 2022.
So far then I cannot get any of these advanced searches to give me a total of 431, although that looks realistic to me.
Anyway, this gives me a really good start whenever I'm looking for a topic that I'm pretty sure I've discussed before, thank you.