We are just starting to ttc this month and I feel like I know just enough to make myself nuts.

The short version is:

Is it still worth it to chart this month if I botched the first three temps? (I assume yes but it there is a good reason to skip it I would rather know now than figure out later that I was making myself crazy for no reason )

Any suggestions on a thermometer? I have two, one is going in the trash, it doesn't beep every few seconds which was a big plus in my mind but it isn't back lit and it doesn't store the last temp. The other one beeps every few seconds but is back lit and stores the last temp, it shows temp to the tenth of a degree not hundredth -- it seems like there is some argument about which is better?

If the thermometer I have is my best bet, should I replace the battery? I temped for 4-5 months with it about 5 years ago but it seems to be working fine.

Thanks!