Had my period Dec 19th. Sex on 27th. Three days spotting Jan 4th 2 light one heavier. Missed period yesterday. I'm confused!!!

Check. Periods do become less regular as menopause approaches and this may be the only reason but pregnancy is also a possibility so, if you have been having unprotected intercourse, check a pregnancy test and, if it is negative and your period still hasn't started, repeat it in 3-5 days.Hope this helps.
Protection? If not using birth control and condoms- get checked for pregnancy. See your gYN for mediciaaltion to regulate your cycles and hormonal evaluation. Also, get thyroid and blood sugar evaluations.