That almost looks like one of Setsuna's!!! May be female, but the ventrals are really long. The egg spot isn't always a good way to tell, as I have a male that has an egg spot. Look for longer, fuller ventrals. I also have a female with male finnage, but she is definitely a female. She has a shorter, fuller body as well. Males will have longer thinner bodies than their female counter parts. Sexing a betta is really hard when it isn't obvious, but it's really fun to figure it out! Unless you're like me and have a sorority going and find out you have a male with a bunch of females...NO FUN!!!
If we are made of cells, then a scientist who studies cells is actually a group of cells studying themcells!