I'm 18 as well, and ive had a few. Symptoms are common and possilbly painful urination, and maybe some blood.
Go to the store and get some Pholsphiorus pills, Or consentrated cranberry pills. Drink alot of cranberry juice!! UTI meds are over the counter these days
I agree that you have UTI but I think that you should visit your doctor about this matter.
I know that UTI is caused by a bacteria and that you need medications such as Bactrim and Amoxicillin, and these are antibiotics, and I think that you have to see your doctor because of this. As far as I know you can’t buy antibiotics in the pharmacy without prescription.
And I think it would be wiser to see your doctor and to confirm that you have UTI and you can do this by doing urine and blood tests.
And if you leave UTI untreated it can spread to the bladder and cause some serious complications to your health.