first, it Wicca or Wiccan, not Wiccanism.
don't feel bad, everyones different, so people worship in different ways, some celebrate daily, others monthly, on Sabbats, or never. if you feel bad, try to do something about it. if you know a Sabbats coming up but you can't cast a circle, figure out what you can do as a tribute or offering. Ostara just passed, say you buy a plant, or plant some seeds. if you don't want plants, dairy's traditional for the holiday, pour some milk outside. even something as simple as a blessing or chant is enough.
sit and meditate on the question, the answer should come to you. don't feel bad if you don't cast a circle for every single thing. if you do feel bad though, try to achieve a goal. when i started getting more serous with my studied, and i started feeling bad for not casting circles as often as other pagans i knew, i made a goal to do something on each Sabbat, then i made it a point to have a circle on each one. it was slow, and i know how someone can get lazy, but i did it. i don't cast circles for the esbats but i do say a protection chant on the full moon.