Well, it's been 11 & 1/2 months that I've been nursing my daughter!
It all sounds perfectly normal to me.
As you have noticed, your body seems to be able to respond and make milk as it needs to for the pump or a nursing session, and you don't actually get to feel full. This is also normal.
Your daughter does seem to have made up for less breastmilk while you are working by increased nursing while you are at home. This is common too.
You can certainly gradually drop the pumping at work, and you will still have the supply you need to nurse at home.
Even if you choose to nurse for an extended period of time, say two or three years or longer, and you are down to one or two nursing sessions a day, the supply will match that demand as long as the nursing continues.
To safely drop the pumping at work, to ensure no mastitis, you would be better to reduce the length of time of one of the sessions that you plan to drop first, until it is very short, before completely dropping it. Then do the same for the other one. In other words, take it very gradually.
Actually, if your daughter is having several nursing sessions a day, there is no need whatsoever to introduce cows milk at this stage if you don't want to.
It is a convenient source of calcium, but there is more than in enough calcium in the amount of breastmilk she is getting, given the number of nursing sessions she is having.