No allergy, but since I'm pregnant, I do not stop having a runny nose, sneeze, stuffy nose. Nothing works. And it's worse and worse. I do not have many moments of respite. Can I use aloe vera and how?

You probably have a pregnancy rhinitis, related to pregnancy hormones. The only really effective treatment is waiting for the end of pregnancy. In the meantime, you can practice nose washes based on sea water. It is also possible to use when you are at home, nostril retractors. If this is really very troublesome, your doctor may prescribe a local treatment.
Alternatively, complementary medicines such as homeopathy or acupuncture may be attempted, as it is better to take as few medications as possible during a pregnancy.