When girl starts to act flakey and you are not experienced with girls then its good time to send that girl to hell and start date new girl. Really 3 dates are time when it usually ends cause by then you both start to see who the person really are and then interest gets stronger or weaker. Weaker for her in your case. Girls dont talk directly to not to hurt your feelings. They cant say no or I dont like you or this or that. They rather keep quiet or start to avoid progress. You wanted direct answer from non logical emotional creature who dont want to hurt your feelings. Of course you didnt get the answer you wanted.
Yeah its confusing when girls messages you after it ended. But say to her either she agrees to meet or dont message you at all. You might lose a lot of chances with girls at your uni if you keep fruitless messaging with girl who you have feelings for but are not progressing with.
Doubt kills more dreams than failure ever will