There are several answers to this question. First, ensure that the teacher from whom you take lessons is certified by JEC. That information is easily available on our website, or by contacting JEC directly. Teachers certified by JEC will have completed all 10 Phases and be qualified to teach students.
Also, ensure that the curriculum you are following proceeds directly from JEC (see JEC design catalog for available phase designs). If the pieces you are stitching do not originate from JEC or Kurenai-Kai, you might not be learning the necessary techniques to advance to stitching the JEC curriculum. Bear in mind that JEC's "Phase system" for organizing curriculum is unique to us and may not correspond to the curriculum of other parties/organizations (even if the generic term "Phase" is used to order it). JEC's Phases I-IX review previous techniques and introduce new ones, so feeling confounded or "in over your head" is to be expected if you have been proceeding with techniques learned elsewhere.