Airline lost my baggage?

So on the 16th of December I was on an outbound flight from Chicago to Kuwait with a transit in Jordan flying royal Jordanian. When I arrived at the baggage claim area my bag had not arrived and so I filled out the paperwork and got a reference number and all before I cleared security.
It's been 5 days and most sources online say if it hasn't been found within the 5 days it will unlikely be found within 21 days and so now I have the issue of trying to remember what was in my bag and its value at which I bought it at and the provision of receipts especially for things I got as gifts for which I never received the receipt for. I have a pair of diesel jeans I got as a gift for example that were about $300 but I feel like the airline would never believe me without a receipt.
Also going along the lines of being broke and not being able to afford my own $300 jeans I'm a college student and my next semester of classes will start by the time the 3 weeks are over and the airport that I fly back to (Chicago) is really far from my campus so is the compensation form from the airline something I can fill out online?
Sorry for the long question I'm really worried I just lost all of my favorite clothes and I have no idea what to do about it.

No. Airlines wouldn't lose your baggage, if they were that bad they wouldn't even land in the right place.

You've done all you can do, we can't help you remember what was in your bag, and the airline has a limit of what they pay per suitcase so if you had a suitcase filled with designer clothes and you had all the receipts they still don't pay more than that limit. That's not just the airline being cheap; it's a matter of laws and international agreements limiting what all airlines are obligated to pay for compensation. You can at least check the status of your lost luggage online on Royal Jordanian's website. I can't imagine that people are required to show up in person to claim compensation for lost luggage. Airline travel, by its very nature, is used by people who could be on the other side of the world by the time things are sorted out. That, no doubt, is why you were given a reference number, so you can use it even if you can't show up in person. Meantime, try to remember what was in your bag and what it might be worth. I don't think most people keep receipts for every single item of clothing they own and it would be unreasonable of an airline to expect people to do it just in case the luggage goes missing. I have some socks that are $30 a pair but I don't have receipts for them.

I remember there being some prototypes for my business of which the maxium allowed claim should cover

Just file a claim with your travel insurance

No travel insurance? You're screwed