That's a great pic, photoshop the poo out and it's beautiful.
Well, I don't see a beard or even a trace of a beard. And based on what I've seen on Aquabid and the internet, I think Helen is a female. Here's why:
1) Helen's ventrals. Here is a male dragon plakat from Aquabid:
See how long his ventrals are? Helen's ventrals are much shorter and stubbier.
2) Her size. If I remember correctly, you bought her on Aquabid, correct? Most bettas on Aquabid are sold at roughly the same age which is about 3-6 months old or prime age for breeding. If Helen was a male plakat, he would in theory be about the same size as other males offered on Aquabid because he would be about the same age. But Helen is smaller. It's true she could be a runt or something but I don't think so. She looks too healthy to be a runt.
3) The ovipositor. Yes, some males do get eggspots but the vast majority of them don't. And the males who do have ovipositors still act like males, they flare and bubblenest.
4) The lack of a beard. On all males you can see their beard, even when they aren't flaring. All you have to do is look at the chin and you will see edges of the beard sticking out. I'm not seeing this in Helen and that's a really good, close picture of her.
But these are all just educated guesses. Wild educated guesses. And yes, Helen has a long anal fin, but so does one of my girls and I know she's a female for sure.
Basically, there's only one surefire way to tell and that's to get Helen to flare. There's only one other method to try and that would be to put Helen in with one of your male bettas. You would have to monitor them very closely and be ready to scoop one out right away if a fight breaks out. If Helen starts flaring when she's actually in with another male, and shows a beard (judging by her coloring, it should be red-orange), then she's a male and she should have said so a long time ago, haha. But it's also not the safest way to find out. Both bettas could end up with nipped fins before you can separate them. You probably would want to wait a few weeks and see if her behavior changes when she's totally settled in. I would say keep trying to get her to flare periodically for the next month or so.
Anyhow, sorry for the extremely long post. :) Either way, Helen is a gorgeous betta.