I cannot figure it out when is my ovulation date is

I cannot figure it out when is my ovulation date is.

Please help me on that, here is my story:

About the Period: should I count the first day of my Brown spotting, usually have 1-2 days of Brown spotting then heavy bleeding for 2 days(needs to change pads,2 pads a day) then Light and at the end brown spotting. From first day of spotting to the last day of spotting = 9-10 days.

Base on that My LMP past 3 months: 14-22 Nov,11-20Dec ,8-17Jan

When is my ovulation day exactly?

Is my cycle length 26-27 days or 28 days ? when is the best fertile days ?

Should I count my LMP first day of my heavy bleeding or first day of spotting?

I know that I need to add 14 from my first day of LMP and get the ovulation day but want to make sure I know the LMP right.

Thanks