When you "haddest second thoughts" about something, you are experiencing doubts or reconsidering your decision. Some synonyms for this phrase include: hesitated, rethought, doubted, questioned, reconsidered, second-guessed, or had reservations. All of these words imply a similar feeling of uncertainty or indecision, indicating that you have significant doubts about a decision you made or a course of action you are considering. Whether you are dealing with personal issues or more significant choices, it is essential to take the time to think about your choices and explore all of your options. By doing so, you can make more informed decisions that align with your goals and values.