Well, first off, colostrum is kind of yellowish and thick; doesn't look like milk exactly.
Secondly, I suggest you check your pH meter calibration. Did you do a 2 point calibration? (4 and 7) What kind of meter is this?
Third thing, I am not sure what you did with the pressing. You said your cheese was firm. Did you break it up? Cantal is a bit strange this way, it's like a French take on Cheddar (actually it's 1000 years older than Cheddar). You are suppose to mould it to a brick or tomme, then mill the curd (break up that beautiful cheese) the next day, then salt the curd and mould it again for 1-2 days. Is that what you did?
As for the pH level, I have never actually made it but 4.9 after overnight pressing sounds possible. You may want to change your starter bacteria to something that has a better recovery curve where the pH drop tapers off sooner and it begins to go up. (MA4001 would work very well). In any event, using the pH meter is like driving a car using a GPS. Sometimes you just have to use your senses and figure it out. Use it for quality control and logging purposes, just avoid letting it take ownership of the fabrication process.
The wheels look really nice! Keep us posted, would love to see the rind grow on it!