Could be, they say before O your CM should be white and creamy then at O they will be like egg white, in your underwear i read streaks means before O and circles means Oing, (the patterns that it makes in your underwear. Sorry if I lent TMI but wanted you to know.
Could be. would explain those cramps you had on one side It is always a good Idea to BD!!! They say to do it every other day of your cycle. Then there is better odds you wont miss your O days.