Hi Mary, welcome to the board. I am SO sorry you are having all this junk going on.
Let me see if I can give you some ways on how to live with lupus. First, there is not a specific blood test that will give a diagnosis of lupus. The doctor needs to tell you which test is positive. The most common is ana, anti nuclear antibody, which most sle patients do have, but there are some of us, myself included, who have never had this positive. BUT there are other antibody tests which are more specific to lupus, so don't put all those eggs in that one basket.
Arthritis is a broad term. Some patients do have joint pain and even joint damage. This diagnosis is usually given on x-ray showing the inflammation and or damage.
Something that I find helps me to sleep better is to use 4 - 1" foam pads on my bed. It relieves the stress on the primary pressure areas so I can sleep. Without them, I toss and turn all night and wake up feeling like I got worse with the pain than when I went to bed.
The amitriptyline will help you with the depression, but the side effect of it is constipation. You may need to use a stool softener until your body settles out. Try to eat yogurt, salads - summer is coming so gardens produce, and more roughage type foods. Drinking adequate water will help to soften stool too. Also, clear juices will help your gi tract to move things along.
Having a colonoscopy done will identify if you are having other problems in your intestines. It is recommended to have one at 50 yrs, so if you haven't done one yet, you may be due anyway. This is usually done by a GI doctor. Most often the person is given a level of sedation so you are not in pain or problems from it. You need to do a prep the day before to clean out your gut to have this done. One of the not too common problems that lupus can cause is to bleed from the walls of the intestine into the colon. To identify this a colonoscopy is required, so don't delay on this procedure.
If you are having lung infections, you should be seen by a pulmonologist. Lupus can affect the lungs and if not treated by this specialist you can have long term effects. If you are seen by a GP, you may need to ask for this referral.
I often recommend that new patients with lupus keep a journal of your symptoms and pain levels. Take this to your doctor appointments with you. Go through it with your doctors. If they aren't interested, I would fire that bad apple and find a new one who cares what I am going thru. I have fired my share of doctors through the years and while it is hard initially, I find it is best in the long run to have a partner at treating this condition. [I hate to break in a new doctor. I find it is stressful to me, but to have a doctor who won't listen is worse.]
Fatigue is a common companion of lupus. You need to take care of yourself at this point for if you don't you will end up worse off. If you are having this constantly, put it down in your journal and use a scale of 1-10 to rate it. If the doctor isn't interested, kick him/her to the curb and find one who will listen and care for you. Your long term health is at risk here and if you aren't your own best advocate, no one else will be either.
Last, there is a book written by Daniel Wallace, MD who has written this so the average lupus patient can survive with it. The title is "The Lupus Book", not too original, but definitely worth checking out at the library or purchasing.
You will get a lot of support here. This board has people who have dealt with sle for decades and others who are newbies as yourself. The board has people from all over the world, so you can often find at least one person who is here. No question is dumb, and please do not hesitate to ask for help. We each have found our own ways to survive this not so welcome companion.
With summer here, please take care to use sunscreen, stay out of the sun as much as possible. If you garden, do so before 10 am or after 4 pm. I find that my shade garden is a good way to be able to be out during those peak hours yet enjoy the lovely summer days. I've learned to love my ferns and other plants that let me enjoy this passion without putting myself at risk.
Early on in my journey with sle, I learned to keep a beach towel in the car. That way if I had a sun reaction, I had a way to cover the steering wheel and my arms to protect from sun.
Sally
It's a difficult time being in limbo, many of us understand, having been there. The endless tests to narrow it down and rule stuff in or out 
