TTC...having problem with AF

Ok, im a pretty healthy 20 year old about to be 21 next month. Me and my boyfriend are TTC but my periods are a complete mess. I cant get an appointment with my gyno until the end of this month, so i need some advice because i cant wait until the end of the month becuase then i will have to wait for my next cycle to try again. I have been keeping tract of my periods since November, and they have been all irregular. Here are the dates that i got my period on:
November 21
December 29
Febuary 3
March 3 [this one is very light...not 100% sure if its really a period]
Now its seems as my cycle varies from 28-38 days...ugh!!!!
I bought an ovulation test and I want to know when should I test to see when i become fertile? What is the earliest date I can begin testing? Thank you everybody, any advice would be great!!! And yes i did keep my gyno appointment for the end of the month so im going anyways...lol

[mommyluv02]

if you are not sure when you Ovulate my suggestion would be to buy the online kind of ovulation tests you get them in bulk and they are alot cheeper and that way you can test all through your cycle.

www.early-pregnancy-tests.com
or try

www.babycreation.com

[gardenmama]

saveontests.com has the cheapest (I think) - if your periods are not regular, theres a chance are you are not ovulating.  Another free way to tell this is to chart your basal body temp - a great website to learn how to do it and everything else there is to know about figuring out when you ovulate (even using predictor tests) is www.fertilityfriend.com  - I HIGHLY recommend it - you can even plug in your basal body temps and it will analyze them for you and tell you when you may be approaching or have already ovulated.  Check it out and good luck!