As part of the inquiry, the church will investigate what the denomination usually does, and if there are no records, and you were too young at the time to remember, they will usually ask for a statement from someone who was an adult and wittnessed the baptism. If it was done with water, and using the trinitarian formula, and can be confimed, then you may not need to be baptized, as the baptism will be upheld as valid. We need to recall that the Catholic Church holds that the Sacraments are first and foremost actions of Christ, which give us God’s graces, not simple actions of men.

If there is doubt, you would be baptized conditionally. That is that the priest, (bishop or deacon) would baptize you, however the baptism would be done with the intention that if the previous baptism was not valid or doubltful that the rites supplied would be effective only if they were not valid originally.

Normally the minister of baptism would use the formula, “If you are not baptized, I baptize you….”

As for convalidation, if you both enter the Church, you will have to opportunity to take your vows again, and receive the nuptal blessing. While your marriage by the protestant minister is probably valid, as you were not at the time subject to Catholic Canon Law, why waste any opportunity to allow God’s graces to work in your life.