got your pm so here i am with a couple of answers, a couple of questions and a couple of observations. first you are right, 5-10 months is a wide window, i think the most typical for a well kept jacksons would be 6-7 months, but a lot is determined by variables, temps, diet, supplementation, size and health of the animals, are probably the biggest variables, but imo, just about everything you can think of, and probably a few things you cant, are likely to affect gestation. not all xanths display gravid coloration with every gestation, but i think it is probably sort of uncommon when they dont. some hold their gravid coloration long after giving birth. by far the most common gravid coloration is a cinnamon colored camoflage pattern as seen in the left of post #5 of this thread
https://www.chameleonforums.com/expect-babies-soon-36311/index4.html , during the last 6 weeks or so they usually look like they have swallowed a bag of marbles (all lumpy) , its not uncommon for them to quit moving around in the last few weeks, its also not uncommon for them to quit eating altogether during the last week or two. if they were over 6 mths old when you got them, and housed together then i would say there is a strong possibilty that your female is gravid. would probably be best to house them separately and keep them from viewing each other. your help form did not mention cage size, but 75 watts seems excessive. i found 20 watts to be almost too much for an exo-terra 12x12x18 used as a nursery. not sure what the humidity(hygrometer) probe is called. but the temp probe is called a thermocouple sender (not that it matters, most just call it a probe or sender). you might want to triple check your temps and experiment with lower wattages, i find that it rarely takes more than 40 watts, even for a large open screen cage. bear in mind that basking temp can vary greatly, just an inch or so off center of the sweet spot, so check you probe placement and temps carefully. good call to leave the doors open if she will stay in her cage and you are there to watch her. personally i would prefer a (slightly modified) traditional screen cham cage of at least 18x18x36" for a solo adult xanth, (the exo-terra will make an excellent nursery though). as mentioned by a previous poster, a small scale that weighs 0-500g in .1g increments is almost a neccessity to have (make sure you get one with a tare feature so you dont have to calculate the weight of the container.) you can get them for about $20 at most smoke shops. a healthy late term gravid xanth will gain several g a week. in my mind they are a necessary husbandry tool. good start on the gutload, but imo, a complete gutload will usually have a dozen or more balanced ingredients. by the same token a gravid xanth needs a diverse diet and i would strive to offer her as many food choices as possible. silkies, dubia, pheonix worms, and cultured blue or green bottle flies, would all be recomended. one final recomendation would be to review your supplementation. adult xanths in general are sensitive to over supplementation.which becomes an even trickier issue for a gravid xanth (who has increased nutritional requirements). i dont like to recomend specific supplementation regimens (because there are lots of variables & things that could go wrong, and it would be easy to blame it on xanthomans supp schedule) but i will throw out a few general guidlines. gravid xanths have increased supplemental requirements. imo i would bump her plain cal up to once a week. reptivite contains a relatively high dosage pre formed vitamin A, i think herptivite (proformed vitamin A) is a safer choice. my personal preferance for vitamin delivery would be repashy supermin (moderate doses of both pre&proformed vitamin A). ultra sparingly every 6 weeks for a adult male or non gravid adult female, no more than once a month for a gravid female. i would use about the equivalent of a matchead for a dozen feeders, if your feeders look like ghosts, then you are giving too much, imo, anything above 1x a month is risky, i would x the moss for a # of reasons. the only floor substrate i recomend is a perfectly trimmed light colored terrycloth, helps stabilize humidity, cushions falls, makes fecals and escaped feeders stand out better, if you have several cut to size, you can just swap them out and wash the dirty ones, makes cage cleaning a snap. i am not sure it would accomplish anything to do fecal exams on the female, because i dont think it would be wise to treat a gravid female anyway, but it would probably be a good idea for the male and is usually a good idea for all new chameleons. i could go on forever, but i usually get screamed at when i do so, so i will just say good luck, welcome to the cham community and feel free to pm with any other questions. jmo
i havent gotten a scale yet. heres some better pics. thank you guys for your help 
