I selected a Best Answer to one of MY questions and it was counted as a regular vote?

you need to select a best answer within a few days before the public can stop answering (so either 4 days from when you asked the question or a week, depending on if you extended the date people can answer by), if you don't choose a best answer by then, then the question is put to public vote and your vote counts as a public vote too.

=D x

If you just received one point for voting for the best answer then it sounds as if you let the question go to the public vote. Once it goes to the public vote you will only earn 1 point for voting and not the 3 points back for choosing your own best answer. You have to wait a minimum of 4 hours or more to choose the best answer and then ensure that it does not go past the 4 days when it goes to the public vote.

But had the question already gone into general voting status? Did you let the opportunity slide by for YOU to select the BA outright?

if you waited longer than 4 days that is what happened it went to a vote