What to do if the doctor said that under 2 there is no pregnancy, and I have 2.3?

According to the standards of most laboratories (as in your case), the test result for the level of beta hCG from the blood is positive when the concentration of the hormone exceeds 5 mIU / ml. It is difficult for me to answer why the doctor chose the value of "two" as the preferential cut-off limit. You can consult the result with him directly and get this information. In general, the beta-hCG hormone is produced from about the 7th day after fertilization and quickly reaches the aforementioned ceiling of 5 mlU / ml, after which it grows at a very intense rate, duplicating its value even overnight and reaching even four-digit values at 4-5 weeks of pregnancy. If the last menstruation occurred in January and then there was also the last possibility of fertilization, then you would already be at the end of the first trimester, and the result of gonadotropin would be several dozen or even several hundred thousand units (not 2.3). The pregnancy would also be visible on the ultrasound (you do not mention whether the doctor performed it). It is not clear from your entry whether you have intercourse regularly without protection. If so, then an irregular cycle and pregnancy cannot be excluded from later intercourse. In this case, all kinds of pregnancy tests are best done no earlier than 10-14 days after intercourse. If you are concerned, please return with the result of gonadotropin to the gynecologist who ordered the examination. If pregnancy is excluded, the reason for the absence of bleeding should be sought. I enclose additional information: https://www.gdziepolek.pl/kategorie/test-ciazowy