Firstly I'd push for CBT if your not going to take any ADs, I've just finished a course and have had really good results from it, your GP should reallt have been taking to you about this but GPs can be so crap, if your getting nowhere with one then try anothr, its easy to book in with another GP or even surgery in most places and you do not have to give a reason
Heroin is definitely not the answer, please don't even go there, even Tramadol mis problematic, anything over 4oomgs in a day could cause seizure and the anti depressant properties are fairly low along side quite a high risk of dependency.
Have you tried some of the more obvious mood lifters, looking at your diet and taking more exercise? this can often help if its just low mood, but if you have any thoughts of self harm get yourself back to a doctor ASAP, don't be a number in a statistics report.
Best Wishes