The way things work at this place, I'll probably end up maintaining the product until I leave my job.
The reason for not transferring over is that once I do that, they will essentially not let me create features that I think can be done better using my product, because they exist in some other product.
It sounds like there's a lot of "politics" that you're unaware of or not mentioned. Is the project actually in competition with one of your company's products? If they're an open source company, how do they handle community governance and contributions? Do they normally make contributors sign over copyright, like the FSF?
Why do you think there would be conflict over features?
I agree with others that talking with one or more lawyers should be a high priority.
sounds like you created a competing product and made it open source. that spells trouble. Get a lawyer. IANAL
Let me restate this: You had an idea you were so interested in you created it in your off time. You made it open source. Your company likes it so much they want to contribute to the codebase. You, being the leading expert in this software, are the one most likely to be tasked with working on this codebase.
Beyond the obvious "OMG You're going to get paid to work on your pet project!"
the concern being that they seem to want to control it.
Compensation is probably not going to happen. IF it does then you are pretty much guaranteed they will own and control it.
I would advise NOT seeking compensation, and instead saying "omg! I'm so glad you appreciate the work I've put into this open source project. When can I speak to folks about how the current development process of this project and how to submit pull requests?"
Keep redirecting the conversation towards them contributing. If they ultimately say they need to control the codebase just tell them that if they're not ok with contributing to the project they can always fork it. They get the control they want and it's probably not worth suing you and against their best interest to fire you, because you're the leading expert in how it works.
Side note: I'd switch the license to GPL ASAP. Not because I'm a huge GPL fan but because the GPL can be used as a weapon to prevent them from using it without contributing. Or, it is better at that than any other license. It sounds like you're the sole contributor, so that's probably legally sound. I'd also make some quick improvements that they would not want to forgo since it sounds like they already have the current version under the Apache license.