How can i keep a consistent sleeping schedule if my midday nap always seems to offset my schedule?

Naps: Midday naps can throw off night time sleeping. It will be hard but try to avoid the naps, by engaging in some physical activity or other things of interest, and this will reestablish your night time sleeping schedule.

Omit the nap?: While a brief, no more than twenty minutes nap may be refreshing in mid-day, your observation seems to say that it disturbs your circadian rhythm. Insufficient restful sleep at night will increase your need to nap. Total hours don't count if not restful. Waking with an alarm when it is not at the end of a normal cycle, makes it harder to feel alert and rested.