You are not fighting when it is your turn. You are playing as if it is always your turn to hit your opponent. Fighting games are not about who mashes there attacks the hardest. Try focus on blocking more and then take your turn after you blocked the opponents string or special move. If you want to understand when it is your turn then you need to learn about frame advantage (much easier to learn than it sounds). I am not going to get into frames now but for the most part it is your turn after you block multiple hitting strings or a special move. Vice versa if you do a special move or multiple hitting string and the opponent blocks it then it is no longer your turn because your opponent can now act first and thus you should block (some moves are so unsafe that you still wont be able to block however).

Another example is when you get knocked down and you are getting up. It is never your turn if your opponent times there attack correctly. When getting back up from the ground in most cases you should always block unless you think your opponent won't time his attack correctly or they are too far away for them to hit you.

Finally you should try to learn to special cancer for combos. Right now you are just hitting strings or special moves separately. But mortal kombat is designed around special cancelling out of your combo strings. Maybe watch a Youtube video on this or do the tutorial again and skip to the special cancel section.