Based on the picture, I would say that you probably do need more extension tubes and you may also want to check the back focus requirement like Mick mentioned. I have a MC that I have to use an 8cm extension along with my other adapters. One other thing to check is what focal lengths your flattener works with. For example, my flattener will only work with scopes with a focal length of 500mm to 1000mm, so I can't use it with my MC as it's focal length is 1900mm. Lastly, just for focusing, set your camera to it's max shutter time (mine is 30 sec) and ISO to 400-1600.
Good luck and clear skies.
Mounts: Explore Scientific EXOS II GT, iEXOS-100, Celestron AVX
Scope: Explore Scientific AR102, AR152, FirstLight 152mm Mak-Cassegrain, SpaceCat 51
Guide Scope: Astromania 50mm Guidescope (190mm focal length)
Guide Camera: ZWO ASI120MM Mini Monochrome
Camera: Canon RP (IR modification)
Software: PHD2, ASCOM, and APT