Question about Fertilityfriend.com

[MyM&W]

I signed up the other day and I was just actually sitting down and trying to figure out the whole chart...I am not very good with these things

I'm going threw the months and notice that my predicted menses is moving from 22nd to 19th within a few months...I've always started between the 30th-4th always. Whats going on? Do I have the wrong cycle length or something? Help!!
Like I said I normally start anywhere between the 30th and the 4th, It used to be every 3rd of the month but that stopped after 4 months lol...but my periods usually last 5-6 days. So would my cycle length be 25 days?

[trying4more]

It will just predict, doesn't mean anything is wrong. Keep inputing your cycles, and it will balance out eventually!