One most common explanation for a female gecko is that they ovulate throughout the breeding season, and right now we are still in the breeding season although towards the last couple of months of it. So she could very be ovulating and even gravid, thus why she lost her appetite. There are ways to tell if she's ovulating or gravid, if you take pics of her stomach people here can help you identify.
As for you guessing on parasites, you can't guess on it. There's no way for you to know one way or the other without having a fecal exam done. It usually cost only around $30 to get a fecal done. So if you suspect parasites or even think it's a remote possibility, get a fecal exam done to make sure.
I'm not a fan of hand forced feeding unless it's for a recovering gecko too weak to hunt for themselves. A perfectly healthy looking gecko should eat when he/she is hungry. Forced feeding can be a stressful and traumatizing experience for them, stress is one of the biggest factors in a gecko having lowered immune system. And when their immune system is lowered, they are a lot more susceptible to parasites, diseases, and such.
Now if she was indeed ovulating and gravid, then there's absolutely no reason to be feeding her when she doesn't want to eat. They go through this natural cycle every single year between January and September. They often go off food, some longer than others. But they'll get back to feeding right again after they are done ovulating.
So for you, I would first stop forced feeding. Get a fecal exam to rule out parasite issues. If she checks out clean, then double check on husbandry, and leave her alone. Stress alone could cause her not want to eat, so you want to give her as little stress as possible. Good luck