15k in adult, in most cases, is nothing, to be honest.
Twitter is full of "follow4follow" + you said it's old, I guess you are not active there and looking to make a comeback...
Tweet something and see the activity, wait for an hour, let us know what's going on if you want, of course, so people can help you out.
Anyway, build up your comeback, do not even think about affiliate links straight away tweeting just like that.
Test it for few days, let the people know you are back and, just go slowly...