Woozie, more women seem to get BFNs at 9DPO than BFPs. Wait a couple more days to test again. 11 – 12 DPO is much better for accurate results. As long as your cervix remains closed that is the main thing – it can rise or fall, get firm and soften again – it might not take on a real pregnant feel of high, soft and closed for a couple of weeks after a BFP. Sleeping nude, or with an extra blanket won’t impact your BBT – your core temp is fairly stable and won’t get thrown off by minor changes around you while you sleep (unless you wake up sweating bullets or freezing your butt off!)… now if you sleep with your mouth open and temp orally, your temp can be off a little due to that.