That is a lot of loss to suffer, many here know what it is like unfortunately.
No one can say for sure what is the reason though, fibroids or other, but to have 3 losses and a bfn from DE make me think there is something else going on besides bad luck
You might try asking on the pink board about your fibroid question, there are many who had them removed before finding success (AngMc comes to mind).
As far as your insurance not covering the procedure if you don't do a fresh transfer, as long as everything else is paid for up to a freeze-all, I'm thinking you would only be responsible for a transfer fee later? (FWIW I did a freeze-all, the FET after that was @ $3000...the "expensive" parts of the cycle had been completed already, and we had a credit from not doing the fresh transfer.)