I have been researching "baking powder"  -- and I can't find it available in Brazil either.  In some countries, flour actually comes with a yeast to help make the pastry rise.

So here are my ideas:

What did your mother use to make her pastries fluffy?  That may provide an answer.

Or -- it's possible you can buy your flour in fine form and not need to sift it at all. .

Or, you could use the recipe without baking powder, using the wheat flour you ordinarily use, and everything may be fine.

Or, you could complicate the recipe a little by separating the yolks from the whites of the eggs.  Beat the egg whites until they make peaks when you lift the beater from the mixture.  Mix the yolks in when you are combining the dry and wet ingredients.  Then after you have mixed the batter until it is lumpy -- at the very end, you can add the egg whites by lightly folding them into the batter.

If you choose the egg whites approach, then you must ignore my hint to let the batter "rest" in the refrigerator before using it.  Instead, you will make the batter right at the time you wish to make the pancakes.