Whether you call your research "mixed methods" depends to some extent on how you plan to use your open-ended questions. If your goal is to convert them into variables that will be part of your ongoing quantitative analysis, then this is referred to as quantizing (or sometimes quantitizing). Some people consider this to be mixed methods, but others do not because it fails to make any use of the classic concerns of qualitative research, such as meaning and interpretation.
Alternatively, if you do want to use the information from the open-ended questions to interpret your quantitative results, then that is undoubtedly mixed methods -- probably with an Explanatory Sequential design.
thank you David L. Morgan, I use open-ended questions to provide more in depth understanding of the quantitative date i.e. the answers to questionnaire on a Likert scale, there is no inferential stats involved - just answers to the statements plus content analysis results that are informative of those , I would not class it as ES the data was collected all together.
An Explanatory Sequential design has more to do with how the data are used, rather than when they were collected. So, if you establish results with the quantitative data, and follow-up by using the qualitative data to help understand those results, then that is QUANT --> qual.
But, if you are not producing any quantitative results, then it sounds like your design is probably Complementary, in the form QUANT + qual. This is especially likely if the qualitative data help you go beyond the content covered in the quantitative data.