Have lost 17 lbs. in 2.5 months. Taking only calcium pills. Concerned about health issues. 42 yr. old female. Have eaten nothing else, except coffee, diet coke and beer.

I think it sounds pretty good, that is basically what I have been doing some days, too. Only I use all nuts, I'd get bored of just one kind. Nuts have lots of protein AND just a little carbs, so it seems to me it's pretty balanced. Plus you're having veggies. Sounds about perfect to me! But feel free to ask your doctor about it if you're very concerned.
I heard beer is pretty high in calories. Also I read that diet coke is a lot higher in carbonation than regular, and carbonation is actually an enemy of fitness plans... you need plenty of oxygen when you exercise to lose weight, and carbon dioxide is what you're trying to expel.

Cut your coffee, diet coke, and beer intake down to close to zero.
You've got an unhealthy diet. Almonds, avacados (high fat), olives (high sodium content), tomatoes, and green beens are defiently NOT enough.
Add more fruits and veggies to your diet, an occassional meat meal, exercise (a lot), and add a multi vitamin to your diet.

doesn't sound healthy at all. No protein, not complex carbs, few vegetables.

I hope you are eating a lot of beans to get your protein and at least take multivitamins If you're going to be eating like that and add protein shakes in your diet.

Aren't you just going to bounce back?
Just make healthy food choices in general! Stop limiting yourself! Just don't eat unless you're hungry.

don't you know that avacado contains a lot of fat too?!
and this is not enought for you daily basis
at least eat small portion of meat, milk, and grain bread

You should add some brown rice to the mix with the green beans. Eat them together. Thatll give you the protein you need for this diet. I would include black or kidney beans or chickpeas to the rice mix, as they are high in protein and fiber.
You should inlude an apple a day for the fibre, vitamins and minerals, and a banannana for the potassium factor. Potassium helps fuel the muscles including your heart, as well as many other functions.
Take a multivitamin and mineral every morning with your breakfast.
You do need some fats, which the avocado and olives alone cannot supply enough of, so you should consider using cold pressed olive oil in your diet as well as flax seed oil to get the beneficial omega 3's to your brain.
Maybe consider green tea over coffee, normal coke over diet because aspartame is deadly, and of course lite beer over just beer for a lower calorie count.
You should add carrots, onions and garlic as well for their health properties
Theres alot more you could do, yet these suggestions will better your current diet. Good Luck.
Oh, and ideally you should consume 1/2 your weight in ounces of water each day, everyday for the rest of your life. If you try it, work up to your required amount over the course of 7-10 days. Your skin will look great, and the added water will flush toxins from your body, enabling further weight loss.