Can u have a regular period and still be pregnant in the whole process (defining regular period i mean heavy but only for 2 days)?

Possible: It's always possible to get pregnant. Home pregnanccy tests generally do not become positive until you are about one week late. If that test is negative, repeat it in one week and call your doctor.

Well: You can have bleeding during pregnancy which mimics a period and is often an issue when trying to properly date pregnancy. If it is a true menstrual cycle it revolves around ovulation which will not occur if you are pregnant. Your mystery will be solved with a upt, try that approach.