I have experience with Wattpad. It "can" equate to good sales from Amazon later but it takes A LOT of work.
Wattpad for me never garnered as many reads as you've had, though. Congrats!
In truth, you really have to decide what you want to do as an author. Do you want to make it a career or is it more of a hobby?
If it's more a hobby, I'd say keep trying Wattpad and other online platforms. I've seen the most reads from Scribble Hub, myself. You can set up a donation thing through Ko-fi and post the Ko-fi link on your "about me" on Wattpad.
If you also have a blog or website, or even a Twitter for people to follow you, do weekly shoutouts about your Ko-fi. It takes time to get fans but if you're writing is clean and engaging, they come.
That's just a little way for your Wattpad stories to be profitable without much more work on your part. *winks*
However, if you'd like to make it more profitable, definitely think about self-publishing through Amazon. There are tons of tutorials out there, and maybe so much info it's confusing. It is super easy, though you would need good editing and good cover art to make an impression.
If you want to self-publish your 1st novel on Amazon, I would suggest adding to it some how so it's not the same thing you have available for free on Wattpad.
Add a side story, or re-edit the novel. Something to make it different and worth it to fans who've already read the novel.
Or you could leave the first one free on Wattpad
and self-publish the 2nd novel on Amazon. It's all up to you.
Both methods require work on your part, but with that many reads on Wattpad, you need to keep your fans wherever you go next.