Wow! That's a huge Tsh!
You will need to be monitored over the next few months to finely tune your dose, and over the next year and then once a year OR if you start feeling unwell again.
It's VERY important to have Tsh below 2 and thyroxine raised in first trimester if you have another baby,
Please find out more about your condition; understanding it does help you manage it. I've had it for 20 years (got it quite young) when it's well managed in very well, very fit, lots of sports etc. When not well managed it's awful.
It's a chronic condition for life. Your body is slowly destroying your thyroid and will not be able to make its own thyroxine, hence the replacement hormone. If I didn't take it now I would die - it would take a few months though! I often thing it's like diabetes type 1 in slow very motion. And like diabetes you're entitled to free prescriptions now.
T4 (thyroxine) has a half life of of 10 days so it takes a while to build up in your system (and get out if you stop/ reduce doses) - it's important to remember this.
With a Tsh of that I imagine you'll need a dose increase or two over the next few months, following blood tests of course. You're aiming for Tsh of around 1 but everyone is different. Symptoms can take a while to ease properly - 2-6 weeks, sometimes longer.
The British thyroid foundation have been hugely helpful to me over the years. There's also quite a few medications that can affect thyroxine and vice versa, so always check with the pharmacist. This book lists them too and is EXTREMELY good actually - I'd definitely get it asap! It's by the BMA.
www.amazon.co.uk/gp/aw/d/1903474191?pc_redir=T1
You can feel better if ferritin levels are over 70, vit d good and b12 is good. - worth remembering if you still feel unwell.
Thyroid uk are another helpful website and healthunlocked are too.