It is not uncommon to experience tummy and lower back pain during early pregnancy, as your body goes through various changes to accommodate the growing fetus. However, if the pain becomes severe or is accompanied by other symptoms such as bleeding or fever, it is important to consult your healthcare provider for further evaluation. Regarding the delayed positive pregnancy test result, it could be due to testing too early or a low level of hCG hormone in your urine initially. It's always recommended to follow up with a healthcare professional for confirmation and guidance on prenatal care.