Would you mind sending us the screenshot of the “Extra” tab in Taginfo? It should look like this, this is from a similar card:
The “4kB” at the top tells you that it is a 4k card.
Now, if your card is 1k that is excelent. If it’s a 4k, things become a little more complex. The xM1 and flexM1 are only 1k, but if just the first few sectors of the card are written than that shouldn’t be a problem.
I would suggest you purchase a magic Mifare Classic 1k gen2 card from KSEC (if you are from Europe) and test it out.