Good question (& I'd recommend staying vigilant) but it's probably not an issue. Young snakes are growing fast & using up the nutrition from their meals, but thorough digestion takes time. Snakes are also "designed" to conserve water, so not only do they expel urates (which are soft & moist but not usually much or any liquid) but also, they refrain from "going" (both urates or feces) until they really need to. Snakes do not "go" on any sort of schedule, so it's harder to tell if there's a problem, but if a snake is (1) still eating, (2) not looking bloated just above the cloaca (what some people here refer to as "sausage butt" lol) & (3) you don't feel any hard lumps -almost like marbles- when you gently palpate just above her cloaca (aka vent), she's not likely to be constipated. I'm not saying it's impossible for a snake to become constipated (or blocked up due in part to swallowing undigestible substrate), only that it's unlikely.
Preventing constipation is straightforward: keep proper humidity in the enclosure, provide clean drinking water always, keep in a large enough home so they can move around normally, & whenever possible, prevent accidental ingestion of substrate- they cannot digest it, so feed on a "plate" of some kind when you can. And understand that two weeks for a snake not to go isn't extreme like it would be for a human.