yummummy, how old are they, how old are you? Can you wait another year, see how they are when they're a bit older?
I've two boys, a 2yo and a nearly 6mo and I'm not sure whether I'll have another - but I do know that I don't want another till these boys are older - I've done a small gap, love it, wouldn't change it - but want to see what it's like to have a big gap, if I do have another one.
The Chinese calendar stuff, all the "oh, if you don't fart for a week you'll have a boy", "if you eat ear wax after every meal and stick a leprechaun up your fanny, you'll have a girl" stuff is tosh, IMO.
It's like the old wives tales about carrying out front meaning you're having a boy (though some say a girl), craving oranges meaning a boy (or was it a girl), etc, etc.
Whatever you have, it's right for your family.
Good luck - and don't overthink it