Implantation bleeding is a common occurrence during early pregnancy and is usually nothing to worry about. It can manifest as a light brown smear when wiping and may happen sporadically. The absence of cramps, pain, or backache is also normal in many cases. However, it's important to consult with your healthcare provider to ensure everything is progressing as expected. HCG levels can vary between individuals, so it's possible that your estimated gestational age differs from what the apps and doctor have suggested. Your healthcare provider will be able to provide you with accurate information based on your specific circumstances.