Dolly, my baby was like this. I am sure if you search on here you will find endless threads started by me when my son was around the same age as your daughter. It was just the mmost awful experience of my life. We felt just like you describe, exhausted and I just wanted to run away. He cried endlessly, just didn't matter what I did, although weirdly, he did sleep well at night time but he refused to nap EVER and screamed constantly until I walked around with him and juggled him about! He seemed to need constant movement and stimulaton.
If you research Dr William Sear High Needs babies on the internet you may find a lot of helpful info. You don't have to take all his advice, it's a personal thing and every baby is different (for example he recommends co sleeping with your baby but my ds slept well at night in his own cot thankfully! If I tried to put him in with us, he was restless and thrashed about and was more likey to wake up). But it was very useful to me to know that I wasn't alone and there were other babies like this.
We had him at the doctors, health visitors all the time but there was never any medical reson given for it. Tried reflux medication, changed his milk, cut out dairy, nothing worked.
All I can tell you is that it did improve steadily. VERY slowly. By his 1st birthday he was walking and whilst still clingy and sensitive, he was bearable! Gradually our life returned and ds cheered up dramatically once he could talk at around 16 months.
It was hard work but it's over now. Our beautiful son turns 3 tomorrow and I couldn't be happier with our life. It was so worth it. He is just the most polite and chatty, funny little boy. It really doesn't last forever I promise. Sorry I seem to have rambled on as usual but I'd go get her checked at the doctors to rule out any other problems or maybe increase the reflux medication but other than that all you can do is cope day to day and I promise it does get better. Some babies are just harder work than others.