Menstrual cycles that are shorter and come closer together can be a sign, but there is no way to tell whether the luteal phase or the follicular phase is short without testing for the LH surge and counting the days from menses to the day before LH surge (measuring the follicular phase) or counting the days from the LH surge to menses (measuring the luteal phase). If it is determined that the luteal phase is less than 13 days, that would define a luteal phase defect (LPD). Infertility and early pregnancy loss is also a sign.
Let MyMonthlyCycles do your counting! Simply use the free fertility calendar to track your periods and LH Surge, and run the Fertility Cycle Phases Report or Chart, both of which show your follicular and luteal phase lengths.
LH Surge detectors - a.k.a. Ovulation prediction tests (or kits) - are a simple way to test for your LH Surge. You can double check your LH Surge by BBT Charting.