type doesent change, just your perception about yourself changes, if you dont know the real you or perhaps you have wrong definitions of what type is.
why do you think that you are sometimes using SeFiTeNi and other times FiNeSiTe?
cognitive functions are tools.
so, you can teach a stone mason how to craft stone, no, they _might_ nevr master another set of tools, while they just as well might do if they poses the will to.
and as it happens, we dotn start with these tools, we try and mash them up until we figure one set which we prefer over the rest.
if you flipped yourself, youd experience the immersive total sudden change of world view yourself, it doesnt leave any doubt if one moment you experience earth as earth, and the next everything has a philosophical/fantasy like feeling of depth to it. (while with depth you lose clarity of wide view. aka why i dont stay that long in my INFP nor INTP flips. + philosophizing about whatever is in front of my eyes is kind of ridiculous,(as it doesnt make any progress at all into any direction) while i know from experience how wonderful that feels.)
or like for me, i love imagination. i just love it, yet for some cognitive reason i've lost motivation to experience what i love most. i just cant experience it like i used to. doesnt feel the same. neither does music feel the same way it used to.
time to learn my old tools again. (negative experiences can inflict such changes in cognitive preferance as like the effects im describing. avoidance of ones Si, ones own perspective, which is directly connected not in processing to the Ji, but in strength. stronger Pi equals stronger Ji, and abandoning Pi leads to deprivation of Ji as well, aka extroverted personality disorders. mh, at least i know what to do to get rid of my flip flops. and the flips are caused due your longing to experience what you are depriving yourself from, with alternative means as facing them by your primary set of tools would mean facing your fears.)
and self perception is only the intellectual ability to actually see what you anyways are, even if you dont see yourself it doesnt mean you arent what you are nor if you see yourself wrong way, it doesnt make that wrong way you.
while you seem to refer the first cognitive preferance humans find is somehow set in stone, well its not. we always poses all the tools, some we are better at thanks to experience with them, while those we use less not.
and also as others are mentioning, other people have influence over your type.
for example, spend long time in wrong company and your head will be spinning in the end, and youll be glad to get your lone/or with cognitively similar people time to recover into your usual self.
especially if you form strong connections to others, the influence will be greater. just, dont try to connect Ji to other persons Je or the other way if Ji and Je are of same element, as this causes negative changes to both individuals. meaning dont force Fi's to connect onto Fe nor Ti's to connect onto Te. loose connection is only diplomatic approach there. and forcing Se onto Si is rather intrusive as well, for an intp you know this.