Must I repeat the prayer that I prayed abridging and combining at home before traveling, knowing that I made a mistake in doing so and that I am afflicted with excessive doubt?

The prayer that was performed shortened at home, where it was not permissible, must be made up. If it is determined that one's responsibility (dhimma) was engaged by that prayer, then it is not absolved except by making it up with certainty. If the doubt is due to waswas (whispers/obsessive thoughts), then one must distract oneself from it. If it is highly probable that the prayer was made up, and then doubt arises, there is no need to repeat it.