"I'm still recovering" indicates that previously you've been in a negative/bad state (ie, illness, heartbreak) - "I'm still getting over it" is a little tricker. This can indicate you are physically getting over something...and if that negative/bad state was assumed, "it" is still very vague and can mean a broad range of things. If you were to say this, without establishing what "it" is, you'll probably get a follow-up question.
In the case of an illness/bad-experience..."I'm still recovering" sounds more natural.
Hope I helped.