Peace and mercy be upon you,
Regarding your previous actions, there is no need for distress. The intention of a person is clear within their own heart. Showing off that invalidates an action stems from an internal focus on a purpose other than seeking Allah's pleasure. It should not be so ambiguous that one is unaware of their true intention. Yes, sincerity and intention have different levels, and some forms of showing off can be subtle. Therefore, those who strive towards Allah are careful about their actions, as this reflects a greater commitment to fulfilling what is desired.
So, let go of the past days and focus on hope and mercy. One aspect of the mercy we seek is that our past actions, done for Allah's sake, may be accepted despite any impurities mixed in. We can never be certain of our actions being accepted by Him, but we hope for His mercy to accept our deeds.
As for your future actions, there is no harm in developing a new habit that is closer to sincerity, which is to keep your deeds between you and Allah. This does not mean that if they become known, they would be showing off or cause distress, but rather that the general nature of these actions should remain between you and Him. This is undoubtedly closer to sincerity.
However, this does not mean we should never mention our good deeds to others for good reasons. Sometimes, in the context of teaching, it is necessary to highlight some of our good actions to encourage and influence others positively. Showing goodness, whether through actions like charity or through words of gratitude, is also commendable. As the verse states, 'If you disclose your charities, it is well.' This means that revealing and announcing them is good, and there is no dislike in doing so.
Thus, while concealing actions is closer to sincerity, there is no necessary connection between mentioning an action and showing off. Therefore, do not create a connection or distress from it without reason. We hope for Allah's acceptance of all our past actions, and out of fear of Him, we strive for the highest levels of precision in how we perform those actions. When fear and hope are balanced, our faith will be established in our hearts, God willing.
May you be successful in all that is good.