Any suggestions

So I charted late in November and began a new chart in December.  Now according to Decembers chart it would look like I may be getting a BFP, right? Well I'm cramping my hpt is stark white and it looks very different than lasts months in terms of temps and where I fall (my cover line). Any thoughts. I'm think I'm giving up this temping charting thing it's really confusing even when you follow things to a T.