Personally, if she eats, poops, and gains weight, I think that's good enough. If you don't have a gram scale yet, get one so you can monitor her weight. Parasites are known to make leopard geckos lose weight, so that's a sure sign (along with other things such as your gecko stops eating for an example) that there may be parasites. If you are doing all you can, which you are since you have done your homework, then your leopard gecko should do well.
I'm not against a fecal exam or a vet visit, just that it's a tad overkill unless you actually suspect something. I'm totally for a fecal exam if your leopard gecko starts losing weight, or stops eating, stops pooping, starts to become inactive, etc.. Or a vet visit for sure if anything major or something noticeable goes wrong. But if you got their environment setup right, you dust your feeders, you gut-load your feeders, chances are you'll have a healthy gecko.
I can't recommend weight monitoring enough, it's like one of the best ways to check to see if something is wrong with your leopard gecko. I had a female that stopped eating for 3 full weeks. It freaked me out a bit, wasn't sure if she was ovulating (no obvious signs) or not. Then I started monitoring her weight, she didn't lose any weight so I was able to stop worrying. And sure enough, on the 4th week, she pigged out. She has been eating every single day, getting a big fat juicy dubia roach every single day.
So in my opinion, as long as your leopard gecko eats, poops, and gains weight, chances are your gecko is healthy. Save the money for raining day, in my opinion
