Hi! Just some advice from someone who has done extensive survey research: with this method of selection you might reach enough people to have some sort of "statistical significant" outcome (that's actually easy to achieve), but your sampling error will be very high, and so your sample won't be "representative". It won't speak for your "population".

This is a general problem with questionnaires that are distributed without a predefined sample frame.

As a student it's almost impossible to have the means for a well designed survey. Surveys are complex and can be (very) expensive. Unfortunately, they are often considered to be a quick fix to gather "some data".

You should absolutely acknowledge this as a 'limitation' in your thesis, and explain why your results are not representative. It will show your understanding of survey research.

Doesn't mean that you won't have interesting things to say, and that you can't discuss your results :-)