Absent periods - is thyroid to blame?

[tintinenamerique]

A newbie here, posting in frustration and desperation. Really, I'm after some mumsnet wisdom/advice/TLC.
Came off the pill (Cerazette) in December 2010 to begin TTC. Period took a year to come back, and then was irregular with long cycles. Managed to conceive in June 2012 and had a miscarriage at 11 weeks. Fell pregnant again in October and after discovering some major heart defects, decided to terminate. This was January 2013. It is now July 2013 and I have had two periods. Looks like my long, irregular and downright absent cycle is happening again.
Dr tested bloods, flagged up underactive thyroid (free F4 is 8.7, TSH is 3.6), but said to come back in two months to retest.
In the meantime, I am getting frustrated and impatient that my periods are so infrequent, and I am therefore failing to conceive.
Am I being fobbed off by the Dr? Is it likely my thyroid stopping my periods?
Can anyone shed any light on this at all?
Thanks

Hello, sorry you've had a tough time. I'm hypothyroid myself and understand TSH is best kept under 2 while conceiving. Yours is higher than it should be, but for some gps still within normal range and I wouldn't expect trouble conceiving with that TSH.

What is the other value? I've heard of free t4 but the range is different from the number you mentioned, so I'm not sure if its too low.

If your GP says your thyroid is under active, then why won't he prescribe medication? You could just get a low dose of levothyroxine, say 25 mcg, and see how your levels improve. Do you have any symptoms of hypothyroidism? If so, the Levo should definitely help.

Um, yes free t4. Apparently the range is 9-25. Mine's under, but only just. I too am wondering why the doc wants to retest rather than prescribing based on these blood results.
In terms of other symptoms - I'm always exhausted and have achy legs, just put these both down to doing lots of exercise.

Well, they could be hypothyroid symptoms. I was always tired as well and had really heavy legs. This improved after taking meds. I just had a high TSH btw, t3/t4 was within normal range. Although many people still have symptoms when they're within normal range. That's why some people strive for the higher range of t3/t4.

If T4 is under normal range, I can't understand why you wouldn't be put on meds! It takes at least 6 weeks for levothyroxine to start working anyway, so I would say the sooner the better. But maybe your gp has reason to believe it will correct itself? I wouldn't know how that could happen though.