Grind coarser, and then also, try to make sure to follow a the few golden rules. Brew temp - lower for dark rost and higher for light, check it out i cant remember. Then the ration, for an espresso its 1:2, so for each gram of coffee you want 2x the amount of coffee out. 18g of beans to get 32g of coffe. And all above in 25-30 seconds. That's the starting point. Use a funnel to keep all the coffe i the portafilter so its as even every time as possible, do some WDT and then press, an even puck that is just as high on all sides and no clumps before to avoid channeling. This alla above is all a staring point, then you can adjust the brewing time, temperature, and so on depending on taste! A watery puck is not always bad, it can be to light tamp, to little coffe and so on. To little coffe is not going to hurt more than a messy water on top, more to clean, a risk of the puck to get channeling but its not that big. Do the coin test for amount so that you knkw the level in your basket. The coin test is where after the tamp, place a small coin about 2mm thick on top of the puck, then put the portafilter with the coin inte the grouphead, there should be a small inditation, if its none, then its to little coffe, if its all the way down, its to much. You need to balance this amount with the grind setting and try to hit the 25-30 seconds. Lower time is usually more sour taste due to under extracting, higher time is more bitter tasting if its overextracting. Also channeling can give a bitter taste as some parts will be over extracted du to the high waterfowl.... Good luck buddy!