Data Warehouse indexing approach - to verify
You mention that you added single-column indexes for each foreign key in your fact table. Often at least some of the foreign keys have low cardinality so they are likely not useful in an index on their own.
https://www.ibm.com/developerworks/data/library/techarticle/dm-1309cardinal/

They may be more useful as part of a multi-column index which you can design based on the way that you expect users to query the table.

If your workload suits it, then non-clustered columnstore index should be considered on large dimension tables and fact tables. They are ideally suited for data warehouse workloads. http://www.nikoport.com/2016/03/07/columnstore-indexes-part-79-loading-data-into-non-updatable-nonclustered-columnstore/

Since you are using 2014 then non-clustered is the only option if you want to keep constraints and other indexes.