Hey Jessica! One of the most frustrating things about Lupus is that yes, you can have a negative test for ana, and inflammation in the body - even when a Lupus patient is in the midst of a large flare. As for your "Im only 31 years old i should not feel this way" You're right - you definitely have something going wrong in your body, and with what you've described, it does sound like it could be an autoimmune illness, possibly Lupus. (of course, I'm no doctor) 31 isn't young to be having autoimmune, though, as many on here are much younger, or parents of much younger with it.
What I would suggest is that you go see a rheumatologist, if you haven't already. A rheumatologist deals with autoimmune - specifically illnesses with joint issues and pain. In my opinion, that would be your best bet towards getting diagnosed and on the path to feeling better. Even if you aren't diagnosed with Lupus or something specific, they can still try to prescribe medication and evaluate things so you know a little bit more about where you stand and what might help you.
It's a hard journey, I know, but you can do it. After all, you've gotten this far
just remember that you have to be your own advocate.. if a doctor makes you feel unworthy, or perhaps doesn't give you what you need, then they're not right for you - and you should move on and find one who is. Keep pushing to get diagnosed, to get the medical care and treatment that you really need.
But for now, be sure to rest when your body needs it. Let yourself be still and give yourself breaks - you need them. If you try to push yourself too hard, it may hurt you in the end, regardless of whether or not you have Lupus.
Anyways, welcome to the forum, and I really hope that you get some answers and relief soon.