The move 19. ... Qc3+ looks like a good try, but ultimately goes nowhere. One possible line even ends up with the queen trapped: 20. Ke2 Ke8 21. Nb6 Be6 22. Nec4 ....
And just so everyone is on the same page, the way for White to follow up 18. Rxa3 Qb4+ is with 19. Ke2 Qxb2 20. Rb3 and once again Black is struggling.
What we have here, folks, is a classic example of a premature and undeveloped attack, gaining some momentum via a sacrifice, but coming up short against best defense. That is NOT to say that this is not a fun, interesting, and exciting game -- it is every bit of that! And it is also a dang good try, especially if Black is the sort of fellow who likes to go for the gusto and have some fun along the way.