I recommend not using fast fashion 100% of the time since it isn't very good for the environment and stuff. If you ARE financially struggling it can be excused most times.
My best advice is learn how to diy your own stuff. All you really need to start is a simple sewing kit you can probably find in sooo many craft, dollar or household stores. You can thrift to start or find aspects of your old clothes that maybe you don't wear anymore and upcycle it to be something in your style. That's something I did. Cut shit up, it doesn't have to look good at first but it'll be something you made and it'll matter soo much more than hundreds of fast fashion clothes that may disintegrate after 6 wears. Have fun and good luck !