chasv77answered grow question 5 years ago Hello. Your plant is too young yet to have a thick stem. That comes from time, and maybe a slight breeze on the plant, to help it get stronger.
Be careful not to dry out the plant/soil, as it is still dependent on humidity.
If she is getting top heavy, then as MajorComa said, stick some kind of support into the soil, on the side it is leaning, to prop it up, in the mean time.
And yes, make sure the plant is not stretching, due to lack of light.