As you will be drinking lots of water during your Kilimanjaro biking climb, you will be urinating a lot. Also, high altitude makes you urinate more frequently, even more so if you’re taking Diamonix. Using a female urinating device (a funnel) will be a great option to make it easier when there’s no bush or rock to hide behind! A portable toilet tent will be available for the night that you’re camping out, but all other nights you will be using the toilet in the hut.
Regarding keeping your body clean on the mountain, you will be given a bowl of hot water in the mornings and once you reach the accommodation after hiking. Using wet wipes for “washing” your body is what most women do. You will probably not be able to give your hair a proper wash during your Kilimanjaro trek, so dry shampoo may be an option. Regarding your period, even if you don’t expect to have it during the climb, the altitude can mess with your hormones and induce it. Make sure to bring enough tampons and other sanitary products you might need.
Please do not leave any toilet paper, wipes, etc. on the mountain. Pack biodegradable (compostable) disposable bags to put your hygienic rubbish in. You can get rid of these mornings before heading off.