Getting ghosted on a full is a thing, but it sounds like that hasn't happened yet.
Agent Time and Writer Time are vastly different units of measurement. Agents are, for the most part, fitting in query-reading and submission-reading around other work that's actively making them money. It's not that they aren't excited about a particular manuscript, but they are prioritizing the contract that just came in for a multi-book deal, the author who's sobbing on the phone because the publisher sent out marketing materials with her name misspelled, the editor who wants to know why an author has just blown his fifth deadline extension, and their boss who's demanding they grow the agency this year dammit.
In writer-time, we have one or maybe two manuscripts out there, and we're waiting.
At any rate, when you submit a full, an agent automatically thinks, "I have six months to read this," and unfortunately with an R&R, when you resubmit your full, they still think, "I have six months to read this." That's nerve-wracking, but the February submission can't be nudged, really, until August.
Definitely submit queries to new agents. Don't hang your hat on either of these two. By the time August rolls around, you may have another six full requests out there and one offer will trigger a feeding frenzy.
Additionally, start writing another novel. Have something in your back pocket to make the offer of representation even more tantalizing for the agent.
Good luck!