Which one do I trust?

I just took both of these with the same urine. The one on the left looks positive to me in person and in the picture. The one on the right is obviously negative.
In reading the paperwork that comes with each test it appears that the one on the left is more sensitive (25MIU/ML) than the one on the right (40MIU/ML). 
My husband has not so great swimmers. The doctor told us to have sex every other day as a result. I feel like timing is really important, and these two very opposite tests confuse me. I don't want to have sex and not be ovulating. What should I do?
This is also frustrating. I feel like I need a degree in this or something. 
</end rant)