Heidi's Frogen Yozurt Shoppes reported a net loss of $848,342 for the 9-month fiscal year ended Sept. 30, compared to a loss of $383,371 for calendar year 1986. Revenue for fiscal 1987 was $4 million, compared to $4.2 million in 1986. The Laguna Hills company changed the end of its fiscal year to Sept. 30 from Dec. 31, causing the abbreviated 1987 reporting period. "We're a fast-growing company," Heidi's spokesman Brian Pallas said. "Any fast-growing company I've seen has losses." Pallas said the company expects to post a profit in fiscal 1988.