Sweetie, I've been at this for almost 4 years and I'm still lost!
Sounds like you might need a little push from a doc to get yourself regulated. It can be any of a number of things. PCOS, your weight, other hormonal imbalances because of a hypo/hyperthyroid condition, etc. I think you're heading in the right direction when you are saying you may chart. It's a good start to see what your temperatures do. But without some bloodwork and testing, it would be really hard to figure out what is really happening in there.
The good news is that most of us here have already been there, done that. So, you'll get some really good advice on where to start. Call you OB/GYN and let him/her know that you want some testing. The common workup is LH, estrogen, progesterone, thyroid, and a few others. Because of your weight and possible ovulation issues, they may want to do a test for insulin resistance and to rule out PCOS.
They may ask you to come back in the event that you ovulate to test for your progesterone levels again, to see if you did ovulate.
That's just a start. It sounds overwhelming but it's really not as bad as all that. Your doc will be pretty thorough I'm sure (and if he's not, get rid of him!). But make sure that when they discuss your results that you get the actual numbers (none of that "within normal range" stuff!). The reason is because let's say they test your P4 (progesterone) and it was an 8. For your docs office 8-20 may be in the normal range but 8 is too close to the low end of the range for comfort. You'll want to address that with him. That goes for all your tests.
Good luck!!