Are you checking the overnight lows with a finger prick test, as you may be experiencing compression lows, which can happen when you lie on a sensor at night and are actually in accurate readings. Also Libre is most accurate between 3.9 and 10, so readings outside that range should be checked with a finger prick test.
If you're checking that you are too low, it may be that you're over--correcting the lows?? Or for that matter, the highs??