Unless you are completely bilingual, you should always translate into your native language.This is not a criticism, it is how it works in the translation world. I am sure your spoken English is very good and I am sure, it is adequate for certain kinds of live interpreting, but judging from your profile and your post, your written English is not good enough, grammatically or idiomatically, to offer as a Portuguese to English translator.
You seem to have very little translating experience, so I think you should start with offering English to Portuguese translation and with smaller jobs (not cheaper necessarily) and in subjects that you would be comfortable translating. Your interests seem to be in the medical field, so concentrate on these and try to get some relevant translations - Portuguese to English - into your portfolio. (See if you can get permission to translate into Portuguese relevant medical articles taken from journals, or the internet, or from research students etc.)
You offer many skills in your profile. Be sure, when you apply for these sorts of jobs,that you would be happy and confident working in those roles.I think you should start with just one interest and build up from there.