Why are you checking your weight several times a day? It's pointless. R-e-a-l-l-y pointless. Your weight fluctuates naturally all day long -- you're getting no useful information. If you must weigh every day, it should be at the same time under the same conditions. Even then you are going to see fluctuations. Please check out this article:
Why the Scale Lies.
In answer to your question, I have a Tanita scale that I'm very happy with. It does measure BF -- Tanita invented the electrical impedence method of measuring BF. It is NOT as accurate as professional BF measurements by water displacement or a well-trained technician with calipers. However, it can give you a good ballpark on a monthly basis. The caveat, though, is that the most accurate readings are done under very specific conditions; be sure and read the manual thoroughly.