Since Isabella was born in England there would be some kind of record of her arriving to America. However, at that time period typically only the men would be listed on voyage rosters. Women and children could easily be left out.
Some ancestry trees have her father as Thomas Holland, but they are unsourced and thus not reliable. If you found Thomas Holland arriving to America, you would still need to find a reliable source connecting him to Isabelle.
Still, tug on the thread of the possibility her father was Thomas. If you can rule it out your work will help others prevent making the same mistake. If you find a connection, then yay! Good luck!
