#baking issue

I'm having trouble with a recipe and idk what i'm doing wrong. The first time I made them they were great, the second they tasted awful (left a bitter aftertaste) and I just made them again and all of them look different!

Some look like the first time I made them but higher, some looked a bit better than the second time and some look just fucking weird

First time:

Looked smooth and tasted amazing! Best vanilla cookies I've tried. The dough was so easy to knead!

Second time (pics from a video I sent my grandma):

The dough didn't want to come together so I added a bit of milk (the recipe said so) and after baked and cooled down, the cookies left a bitter aftertaste in my mouth (literally. The flavor was good and then BOOM bitterness all over your mouth). The recipe was followed through and through. The differences with the first time are: different oven, different flour brand.

Third time:

These are all from different batches I made today (same oven and flour as the first, same dough for all but divided them in two batches so I could knead easily, added milk as I thought necessary, as the recipe says). It took me longer to integrate the flour and even when the dough seemed pretty good to go there was still some flour left. The thing is, if I add more flour, it gets drier and harder to smooth out but if I add milk (even the tiny tiniest amount) to try and put the dough together again, it gets sticky. I kneaded a lot and it was difficult to do so, it had breaks after using the rolling pin.

The golden one is part of the second batch and I decided to bake them, flip them, and bake them again just in case they were still raw inside bc they raised higher than the other ones so more dough to get baked I assumed.

The taste overall was okay, but they still don't feel like the first ones I made. Some were kinda weird. Why doesn't the dough come together as nicely and smooth as the first time? What am I doing wrong???????