I've also had this happen with a the fancy head broccoli called 'Romanesco'. It grew and grew and made huge ungainly plants but never made heads, or even side shoots. Since then I've purposely started my own seeds of broccoli varieties that produce quickly - the "Days to maturity" number is usually on the seed packet.
But you can eat the smaller leaves and stems of most broccoli and it's very tasty, so you don't need to waste it.
