I am sorry for the grief you are experiencing at the loss of your parents. I pray that you will find God’s peace, and that they enjoy eternal life with God forever.
The “textbook” answer is that they are in heaven, purgatory (temporary purification on the way to heaven), or hell, depending on how they lived their lives and their relationship with God. The Catechism of the Catholic Church says:
1022 Each man receives his eternal retribution in his immortal soul at the very moment of his death, in a particular judgment that refers his life to Christ: either entrance into the blessedness of heaven — through a purification or immediately, — or immediate and everlasting damnation.
It says further that
1025 To live in heaven is “to be with Christ.” The elect live “in Christ,” but they retain, or rather find, their true identity, their own name.
Unless someone has been canonized (officially declared by the Church to be a saint), we cannot know definitively whether they are in heaven, purgatory, or hell. We cannot know that the most heinous murderer did not repent at the moment of death, nor can we know that an apparently virtuous person did not succumb to the devil’s temptation on their deathbed.
What we do know is that God is completely merciful and completely just, and gives each person plenty of opportunity to reconcile with Himself. You must entrust your parents (and all deceased loved ones) to God’s infinite mercy, and continue to pray for them in case they are still in Purgatory and need the assistance of your prayers to complete their purification.
Even if your loved ones are already in heaven, your prayers for them are not wasted; they will assist some other needy souls.
Just trust in God. He is good and loving.
We do not know what they look like. Right now their souls and bodies are separate; they will be reunited at the end of time at the final judgment. In heaven you will know and recognize them in whatever way God permits that to happen. (Again, what is needed here is trust!) We know that at that time our bodies will be glorified and made perfect (no more disease, pain, handicaps, etc.) and that we will delight in being in God’s presence.