It does not look like you had a good catechism.

Did you have a daily life of prayers?

Did you use to pray the rosary, including meditations upon the fruits of the mysteries?

Did you use to meditate upon the solemnities and devotions along the year?

Did you have a usual examination of conscience, as per the proper guide for such examination, and regular confession?

Some people do say "I used to be Catholic" without ever actually practicing the faith.

Lukewarmness is an enemy to the soul. It's fruits are lapsed Catholics.

Any protestant (as you are, although not admittedly) who actually delve into the fundaments of catholicism, becomes Catholic.

Ask Scott Hahn, for example.