I didn't say anything about you having twins - twins run in families so what?
You say you are small - a small baby is not likely to be bumped forward in gestation. Twins are likely to be even smaller and very very unlikely to be bumped forward by 4 weeks at 12weeks to suddenly become 16 weeks.
The sudden jumps in gestation are characteristic of people who come on here and fake.
And no even after all this time I have no idea why someone would want to fake, I don't know if they get pleasure from it or if they are very sad little people, but fact of the matter is that hundreds of them do it and they all make similar f*ck ups.
As I said (twice already this is the 3rd time) I may be wrong - it's almost possible but I will be watching out so just make sure you get your stories straight.