Welcome to our forum and it is quite common to have problems after pregnancy and I'll give you an archived link which might explain things more clearly.
The fact that you are having symptoms, and I don't have much faith in doctors expertise, particularly if you have disabling symptoms and a new baby plus yourself/family to care for. Read from the date September 11, 2004.
If you can get a print-out of your most recent blood test with the ranges and post on a new question and members will respond.
If you didn't follow this procedure, ask for a new test - if they wont, you can get a private one through a recommended lab and get a small discount. They should take clinical symptoms into consideration but unfortunately don't appear to know any or even the most common ones.
First any blood test for thyroid hormones should be at the very earliest possible and don't eat before it as food can reduce the TSH (thyroid stimulating hormone) which is all they appear to take notice of. If you were on thyroid hormone replacements you'd allow 24 hours between the last dose and the test and take it afterwards.
Radd is correct about testing for antibodies plus also ask for Vitamin B12, Vit D, iron, ferritin and folate as these should be optimal too.
When doctors pronounce 'normal' with regard to thyroid hormones, I'd take that with a pinch of salt as we feel anything but 'normal'.
I have just read that you have thyroid antibodies and follow the instructions as you definitely should be given thyroid hormones as Dr Toft (ex President of the British Thyroid Association says so). It is absolutely ridiculous that patients have to go from pillar to post trying to find a solution to their illhealth.
We have had to read and learn and take things into our own hands in order to recover our health as it appears that thyroid hormones are the 'cinderella' as they've forgotten the skill of diagnosing by clinical symptoms and patients 'looks'.
You can say you've had advice from the NHS Choices with regard to the dysfunction of the thyroid gland and discuss Dr Toft's article. Some doctors disregard this but not if they are in the least bit sensible and wish to ease the patients unpleasant symptoms.