What should I do now after having spent all the money I saved for marriage, without having paid zakat on it, assuming that zakat was not obligatory on it?

A Muslim must pay zakat immediately once their wealth reaches the nisab and a full year has passed over it, even if the money is saved for marriage or building a house. Whoever delays paying it while being able to do so has committed a sin. They must pay zakat for all past years in which they did not pay it. If they do not have the money now, it becomes a debt upon them until they acquire the funds. If they are unsure of the amount of wealth, they should act upon their best judgment and estimate the wealth and the number of years.