Could be a number of things.
Too much rennet could be a problem, but looking at it I would say it is something else, such as:
The curd could have been raised to the cooking temperature too slowly (do not exceed 40 minutes). This is a very very easy mistake to make, and one you might not even realize you are making.
The curd was cooked to too high a temperature
You listed the diameter, but what is the height of your cheese? Too short a wheel will loose moisture and dry out. I'd say no shorter than 4 inches if you are going to age it a long period of time.
Pressing should not dry out the cheese, it pushes out the free whey that has already been sweated out of the curd, but it can make it overly compact and hard.
Too much of too strong culture can also dry out your cheese.
What size did you cut the curd? for a large cheese, we cut to the size of a wheat grain or a little bigger (this for a 30 pound cheese) for a smaller cheese we cut maybe to the size of a coffee bean (this for a 15 to 20 pound cheese) for a very small wheel, the curd needs to be much larger, say 1/2" or so. Too small a curd size will make your cheese dry out as it ages. Too large a curd size will make it too soft. (for American consumption, we cut our curds a little bigger than how it would be done on the Alp, as Americans do not like their cheese as dry and hard as the Oberlanders)
From the appearance of the cheese, I would guess multiple factors. My suspicion would be that the curd is undersized and overcooked.
Don't let this failure discourage you though, learn from it and apply these lessons in the future.
For future cheeses, it is better to ere on the side of a little too wet than a little too dry. a too soft cheese is still edible and even can be very good. A too dry cheese is fit only for shredding over pasta, if even that.
Practice makes perfect.
As for cutting the curd to the proper size, this is one of the most difficult tasks to get right. It comes only through much experience. If you plan on always making cheeses out of the same volume of milk, then you can get a consistent size that you find always works for you. We have to figure this on the fly, as our batches are always changing over the course of the season.