Yes, you used a lot initially but it's no big deal. Since it was frozen initially, better to use a lot than not enough.
So about diluting the molasses. If you stop adding molasses and just feed it with flour and water, this is what would happen....
If you dump 1/2 of the starter and refeed with just flour and water, only about 50% of the molasses will remain. Once that gets active, you discard another 50% starter and refeed. Now only 25% of the original amount of molasses remains, so on and so forth. Every time you dump and refeed without molasses, the original amount is reduced by 50% until the residual amount is so small it's virtually undetectable.
So first dumping and feeding = 50% of original amount of molasses remains
2nd dump and feed= 25%
3rd = 12.5%
4th = 6.25%
5th = 3.12% left
And that's with dumping 50% of the active starter. If you were to dump 75% -90%, the amount of molasses would be diluted even quicker. So if you dump 95% of the active starter, refeed with the same volume thatyou discarded, it would take maybe 2 cycles for most of that molasses to be gone.
For now though, you can use this active starter to make dough until you are ready to do a test between fresh CY and CY starter. No need to wait until all the molasses is gone you know. Also you can also save some of this CY starter in dry form to reactivate at a later date, in case you ever lose or get tired of this CY starter.
To do this, just spread a thin film of active starter on wax or parchment paper and let it air dry. Then save it in a ziplock. You can always reactivate it later like any starter, but it will take about 3 days to become active.