If you are concerned about your luteal phase length then perhaps chart your cycle for a few months to see what is happening. OPKs to help predict O and temping to confirm O and document the length of your luteal phase.

For most people the follicular phase varies but the luteal phase remains the same. Obviously not always the case but generally speaking. Mine was always 9 days except when I took vitex for one cycle and then other prescribed medication after that.