Welcome, lexmhll. Peace be with you. No one need fear committing the unpardonable sin referenced in Mark 3:28-30 & Matthew 12:31-32 if they have truely accepted Christ as their Savior. The unforgivable sin you speak of is the blasphemous action of refusing to accept the witness of the Holy Spirit as to who Jesus was, and for what purpose He had come. The Pharisees listened to Jesus' words & teachings, and then rejected the Holy Spirit’s witness to the truths He spoke, and to His very deity. Rejecting Jesus is unpardonable, and Jesus equated that to blaspheming the Holy Spirit.
The bottom line- if we freely & sincerely accept Jesus as our Lord & Savior, we Do Not, Nor Shall We Ever Be Guilty Of blaspheming the Holy Spirit; because we have believed in the Holy Spirit's message and testimony to the truth.
I pray this explanation brings closure of this issue to your mind, and peace to your spirit.