Sounds like you are missing a table where each of your different quoted products is a different record that is linked to a record in Quotes and also to a record in Products.
Invoices, Quotes, and Bills of Material (used in manufacturing) all have the same basic set of tables and relationships. The only major difference is the name of the first table:
Quotes::__pkQuoteID = QuoteLineItems::_fkQuoteID
Products::__pkProductID = QuoteLineItems::_fkProductID
You can place a portal to QuoteLineItems on the Quotes layout to list and select Products records for each given Quotes record. Fields from Products can be included in the Portal to show additional info about each selected Products record and the _fkProductID field can be set up with a value list for selecting Products records by their ID field.
For an explanation of the notation that I am using, see the first post of: Common Forum Relationship and Field Notations Explained