Hi Cassie
I'm another one for whom the zeros cause confusion

I'm pretty sure that the 750 that you've found on Google is the total amount in the pump pack.
Medicines.org.uk states:
One gram of gel contains 0.6 mg of the active ingredient, Estradiol (0.06% w/w).
Each pump actuation delivers 1.25 g of gel which contains 0.75 mg of Estradiol.
I think we have to bear in mind that diff products have different concentrations of Estradiol so like for like comparison is difficult for most of us!
I'd go with Dotty's comparison with the patches. The most important thing, to my mind, is 4 pumps are the most you can use under license, any more than this is off-licence. But clearly needed by some people!
The main thing is, try not to worry and speak with your GP/specialist if you have concerns over your dosage
Suzie