Hi Krista – welcome to the forum.
Your description of yourself/your life could be that of any number of people within our ‘community’ here. So you’re not alone.
When things become overwhelming it’s best to ignore what doesn’t matter until you get back on track and focus on what does matter for the immediate time. I can only give you my personal thoughts which might be wrong of course!
What does matter is that your little girl feels loved and gets decent meals. It doesn’t matter to her if your home is in chaos as long as it’s not dangerous for her. So, start having some fun with her. When you feel better you can start turning your attention to the less important stuff like tidying/organising. It’s important to try to prioritise. Not easy I know – especially when it all seems too much.
Yes you can be diagnosed with ADHD as an adult. I was diagnosed at 49 – because everything became overwhelming – I could have stolen your description of yourself (except for your age and having a little girl!!). 
You do not have to have had or have now, any signs of hyperactivity. You might have the inattentive version. It’s a spectrum disorder.
The bit about childhood comes into things because there should have been some evidence of it in your childhood. So if you’ve always been a little bit like you are now then it’s a positive in determining the problem. It might be that you developed great coping mechanisms in the past and it’s only recently that it’s got out of control because you’re juggling more in a busier life than perhaps you had previously. That’s how many adults discover they have ADHD.
Sometimes it’s difficult to get proof of it in your childhood – maybe you were told at school to concentrate more, or something like that?
However, if all this has come on relatively suddenly then it might be due to something else – so the longevity of symptoms is important. Has something recent triggered how you feel or has it crept up on you?
Please seek help. It’s vital that you see a specialist in adult ADHD – it’s a rare GP who knows what to do. If it is ADHD you have then there are all sorts of tricks that you can use to help with organising your life and it might be that you would benefit from medication? Untreated ADHD can lead to depression if you feel constantly overwhelmed. But you need to see your GP in the first instance to rule out anything physical like a thyroid problem.
If your GP wants to just treat you for depression (many do if they don’t know about ADHD) then demand to be referred to a psychiatrist who specialises in ADHD. You could even print out your posting here and take that with you in case you find it difficult to explain to him/her.
Check out all the threads on the forum and the videos – they’re helpful.
Good luck.
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