I need help from woman who understands and know about BBT charting

Sarah • Recently married not ready just yet to have a child but looking forward to starting a family next year fingers crossed
Hi ladies, I need help from those who know and understand bbt and what it all means! Here's the deal been on this app for almost a month now trying to track my cycle so I can try to prepare for a baby so when the time comes perhaps it will be a little easier. bbt I've been tracking since the 15th wich was second to last day of my ovulation. I had sex with SO in the middle and end of my ovulation. It's been pretty even with maybe a change by .1 or .2 day by until the 11/24. So here's a break down.
11/24 my bbt is 97.8 that's 4 days prior to period being due. 11/25 my bbt drops to 95.0 that's 2.8 degrees. 11/26 jumps back up to 97.7 that's back up 2.7 degrees. 11/27 jumps up again to 98.4 and 11/28 my period was due and didn't come bbt stayed at 98.4. Today 11/29 my period didn't come again and my bbt jumped to 98.5. I have no signes of a period white vaginal discharge and that's all I got. Can anyone tell me what bbt means as far as the change in temp and could it relate to the late period. 
Thank you in advance ladies!!!! 

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