Tetanus complication. For a long time.

Please suggest I am really confused and need your advise: I did take the 5 years tetanus course in childhood. After that I took tetanus shot only when I got a cut from iron. On 31st January this year I took a TT shot (0.5ml) after a cut from rust and again on 3rd October after another cut. But this time the doctor suggested me to take the full course of 5years to avoid frequent shots. But I went for a second opinion before taking the second shot of the course and came across the following replies from doctors: 1. I don't need any full course again as the adhoc I took will give immunity for 10 years. 2. I should not take the full course as too much TT injection can give trouble. 3. 0.5ml TT shots give immunity for only one month so go for it. Please suggest what to do. I am going through anxiety for a long time.