A person should refer to scholars about the rulings of Fiqh and desist from employing one's own reasoning. The issue of dough is different to cosmetics and creams for which reason the same ruling will not apply. In the case of dough the Fatwa given by some jurists was that wudu will be permitted as it was a widespread problem women faced. Ibn Abideen in Rad al-Muhtar, makes clear the basis of this dispensation was need, vol.1 p.288-289. Furthermore it is doubtful whether this fatwa would be given today, firstly because of the existence of new cleaning detergents that help in removing any residue and secondly because in the culture we live in less and less people kneed flour with their handq, thus the need if it exists is not widespread. In any case, if the cream you employed prevented the water from reaching the skin, all prayers prayed in this state will need to be repeated. if you are unable remember the number of prayers, you should make a reasonable estimate. As for the question of sin, it would seem it was an understandable mistake, nevertheless one should ask for forgiveness out of precaution.