Hi coachswife - Obviously there are hormonal issues going on, otherwise you would have a normal and regular period.
Firstly, often with pregnancy it has not been uncommon for women to end up with a thyroid condition. As your doctor has only tested your TSH, that doesnt show much, unless it's waaaaay out. Most times most people's TSH levels are normal, but it's the Free T4 and Free T3 plus Thyroid Antibodies they need to test to know what is really going on.
The testosterone lab range does appear to be a weird range and i'm not familiar with that. Different labs and different countries use different lab ranges so it's hard to tell. As a non-expert, i also think it looks a bit low.
When there is progesterone deficiency that can cause irregular periods. They ought to test all your hormones: estrogen, progesterone, testosterone, DHEA-S.
The fact you were well prior to falling pregnant and were able to fall pregnant shows that during pregnancy your hormones and/thyroid have gone off the tracks somewhere.
I was also repeatedly pushed onto birth control, which i didnt want as i wanted the problem fixed. I tried 3 different birth control pills and they each gave me varying and major side effects and i have not taken them since. I waited a few years as i didn't know what to do as i kept being told that i was fine, my tests where fine. Much later down the track i got tired of my symptoms and crazy periods and i got onto the healthboards and with the information i learnt i went and found a good doctor who found out my hormones were a mess as well as my thyroid, but that all took 9 years. That's why i urge anyone with a problem to learn as much as they can and not accept being told, "you need to go on birth control" or "you might as well get a hystorectomy".
Prior to finding a good doctor, i did start off with a naturopath and along with a herbal mix my periods returned to normal. Not sure if that's a cheaper option for you rather than visiting a doctor who deals in bio-identical meds?
Have you had your ferritin (iron stores) and Vitamin D levels checked? Often people have noticed a difference when these fall low. They need to be up at the higher end of the lab range.
I would urge you to get at least the further thyroid tests and take it from there. Good luck