As you continue to develop your content, consider your market, and research self-publishing options, it might be helpful to consider publishing standards regarding page count.
The most important thing to recognize is the difference between your manuscript page size (which is most likely 8.5 x 11) and your published book trim size (which will most likely be smaller). Whenever a publisher discusses page count, or per-page pricing, it is based upon the size of the published page.
The most common published book trim sizes are 5.5 x 8.5 and 6 x 9, although many publishers will offer several more options.
If your manuscript is 100 pages long at 8.5 x 11, you probably have closer to 200 pages of finished text when the book is published. The good news is, your book just got twice as long, which in many cases improves the perceived value of your published book. On the other hand, some authors will be surprised when they see pricing based upon 200 pages instead of 100. Be prepared.
Keep in mind that production cost is directly related to page count. The more pages your book has, the more it will cost to print. Therefore, most authors keep their books between 100-300 published pages.
Have fun and keep writing.