Answer:
1/3 to 1/2 teaspoons of lemon extract
Explanation:
The proportions you say are ...
1 tsp lemon extract : 2 tbsp lemon juice
extract : juice = 1 tsp : 6 tsp = 1 : 6
If you have 2-3 teaspoons of lemon juice, you have the equivalent of 2/6 to 3/6 = 1/3 to 1/2 teaspoons of lemon extract.