Ideally, the hefsek taharah should be performed as deeply as the finger can reach, and rotated into the folds and crevices of the vaginal walls.
However, as long as your finger was inserted at least until the first knuckle, and you rotated the cloth, the hefsek taharah was valid.
Since you performed one of the two bedikot on day 1, your day 1 remains valid. While one should ideally perform two bedikot daily throughout the seven clean days, as long as one bedikah was performed on day 1 and one on day 7, the clean days remain valid. However, one should not rely on this bare minimum number of bedikot except in a case of great need.
Please feel free to get back to us with any further questions.
B'Hatzlacha!