Wandering aimlessly isn't the same as going forward yet not knowing exactly where you are going. To wander aimlessly means you have no point nor purpose and you're just being carried about by whatever random feeling or thought comes your way. But to go out and not know exactly where you are going or how you're going to get there is different. When we go out, following the Lord's call, we have purpose and aim, namely to please and obey Him, but we just don't have all the details.
This morning I read My Utmost for His Highest and the below was the devotional for today. There are some good thoughts here that encouraged me quite a bit and I pray that it is helpful for you as you seek to follow Him.