Self-publishing means putting it anywhere for the public to see, whether it’s for profit or not. The reason for this is because most publishers want first rights. If you post it somewhere, they don’t get that ability. They want to be the first one to say, “We are the first people people to make this story public!”
The other reason is because of marketing. If your story is published somewhere else, readers aren’t going to buy the traditional publication version. This means that the publishers won’t be able to make money off you.
Now, there are publishers who can negotiate. If you publish through Wattpad (like how some writers did such as Anna Todd, Pandean, etc.) they may turn around and say, “Sure you can keep it up.” But they may only do this if it’s a first draft and that your final draft (what will be published) be completely different. Other publishers may not agree to keep it up, but may allow you to keep up a sample for marketing reasons. It depends solely on the publisher and the contract.
You can continue looking for an agent, as some are okay with it. But it’s best to not mention about the fact that it’s self-published on Wattpad or elsewhere. You can cross that bridge when you get to it (in other words, when someone wants to sign you on).
The other thing you need to know is that publishers and agents have nothing against self-publishing, but only do when it comes to the work you’re querying. So this means you can post other stories and self-publish whatever you like. But if you want to traditionally publish a particular story, it’s best to not post it anywhere.
Having a Wattpad account and self-publishing other stories can help with exposure. Though it can hurt your chances at having a professional, successful debut. But that varies upon many various factors. You just want to be sure that the story you have is what you want to traditionally publish.