youd also have a loss in performance, it would constantly over heat, and youd possibly get some blue smoke coming from the exhaust. wat colour was this smoke when u noticed it the times is overheated?
you could just have a leak somewhere, which is resulting in coolant loss...
a head pressure check will tell u for defo weather the headgasket is gone, and even if it has, you might just get away with changing it.... if it has caused a crack in the head, then getting it skimmed might fix that, or... in a worse case senario youll need a new head, not a whole engine.