Underactive thyroid. Anyone have it?

Hi ladies, so my son is 5 months and if I'm completely honest lately I've been feeling super drained. My son is a great amazing baby and sleeps all through the night. I never have any hassle with him but I'm feeling super tired all of the time. I have at least 8/10 hours sleep at night and then at around 2 pm I have a nap with my son, I try to only have an hour but I find myself snoozing my alarm until it's about half 5pm (my son stays asleep during this whole time) when I get up I feel like my limbs are heavy... when I walk I feel like my legs are stiff and I'm gaining more and more weight. In the last month I have really tried loosing weight and I'm actually gaining pounds not losing them? I've even cut out carbs completely and literally clothes that use to fit a month ago now don't fit? I feel cold all the time and cranky I have headaches all the time and my eyes hurt when I go outside :/ my partner even said my voice has gone very hoarse lately (last 3 weeks) my mother told me that all the females in her family have underactive thyroid and I might have it too. Also near the end of my pregnancy I was a mess I was so so swollen I couldn't move, my mum couldn't even look at my face she said it was too horrible to see me that swollen. I've had bloods done but it takes ten days for results so I'm just wondering does anyone have underactive thyroid and if they do how did you find out what were your symptoms? Was anyone pregnant with it? Is it possible I could have developed it at the end of my pregnancy and the hospital not have known? (They only did blood tests at 26 weeks) and also what happens if I do have it? I just want to prepare myself :) thanks ladies.