If they found blood and protein, then they should be culturing it. I don't know why they wouldn't grow anything. Sometimes it doesn't show up even if there's something there. If you've got pain as well, it sounds like you have an infection.
What is supposed to happen - once it's sent off to be cultured, they identify what they grow (if anything significant) and then they culture the growths again, checking to see what treatment they are most sensitive to and what they are resistant to. That way if the sensitivity comes back that the bug is resistant to what the doctor prescribed, he will call you to come in for a new prescription.
Protein and blood in the urine - if you've got blood, you've also got protein. Plasma contains protein, so you tend to get them together.
Something you can do to help, especially if you get these a lot - get some pH papers and test your own urine for pH. Normally urine is about pH 6, a bit acidic. Much less than 6, it can begin to hurt. UTIs (urinary tract infections) tend to make the urine more acidic and this burns the delicate skin of the urethra, so each time you empty your bladder it cuts it a little bit more, from the outside working in. It also can inflame and damage the sphincters which can then mean they stop working, so you lose control. It can get REALLY bad if the infection goes from your bladder up to your kidney.
If you are alert to early symptoms you can do a few things to help prevent the Urinary Tract Infection (UTI) getting too serious. Talk to your doctor about this to make sure it is the right thing to do in your particular situation, but this is advice recommended to me by my doctor.
At the first early sign of Urinary Tract Infection (UTI) (as discussed with my doctor), I take a sample in a specimen bottle my doctor has given me in advance. By this stage I've usually checked the pH (not testing the sample - I test separately). If the pH is below 6 or if it's painful, I take a urinary alkaliniser and make myself drink at least a pint of water (600 ml). Keep drinking water (again, talk to your doctor about how much) because it dilutes the acid and reduces the symptoms. If you don't drink much water (because going to the toilet hurts, and you want to cut down on your visits) it actually makes the problem worse.
So drink the water, take the alkaliniser. If you keep monitoring your pH and take more alkaliniser as the pH drops, then it should keep your symptoms manageable until you can get to the doctor and begin antibiotics.
Don't postpone doing something, if you feel a Urinary Tract Infection (UTI) coming on. The sooner you do something, the sooner you will get it under control. If you're trying to get some sleep, give up. Get up, do what you have to do, and maybe later you will be able to get back to bed once you've got the dysuria under control.
During an attack, I take alkaliniser to keep the pH at 7, instead of 6. That's because everything is so inflamed that even a mildly (normal) acidic level of 6 is still a bit painful. A pH of 7 is the same as plain water, and it shouldn't hurt no matter how bad the infection is. And if you take the alkaliniser when you don't need to, it will push the pH the other way into the alkaline range. Using pH paper to test is a way to avoid taking too much.
By taking a urine sample before taking any alkaliniser, it means that when they do the dip stick test what they observe will be unaffected by anything you have taken.
With pH paper you don't have to use an entire strip. Just tear off a tiny piece but make sure your hands are clean and dry.
I hate UTIs. I get them too often, but we do know why. I've had loads of investigations, there's not a lot can be done. One really important rule for prevention - empty your bladder within 15 minutes of sex - is often not told to patients. Silly, really. It can make a big difference if you take that precaution.
I hope you can get it healed, they really can slow you down.
Marg