Creating regularly spaced, defined # of points within polygon in QGIS

I used the research tool "Regular Points" to produce a certain number of points within a polygon, but it forms a rectangular grid of points rather than only within the shape of the polygon. Since I need a certain number of points within the polygon, is there any way to do so without trial and error?

E.g. right now only 8 of the 25 points I want are within the polygon, but I want 25 points, so I could increase to 50 points and see how many then appear within the polygon