2very late periods in a row for 1st time. now fsh 6.1miu/ml, e2 63pg/ml, lh 3.2miu/l. 3kg wight gain, tsh ok. no pcos, no stress, but not ovulating. why?

Many possibilities: You say late periods - but if you have periods you are ovulating, maybe just later than normal. There are many other reasons for not ovulating but need further evaluation to sort through: some medications disrupt ovulation, many herbs, supplements can disrupt ovulation, elevated prolactin levels, forms of adrenal disease. You'd need a careful thorough history and some additional tests. Best!