Overtime is called overtime because it is supposed to be above and beyond the normal expectation. This should not be 'normal', but definitely could be in situations where a release is behind, or you're coming up on a deadline, most of which is probably the responsibility of the Project Manager, not you, but you have a role their too.
I would talk to the Project Manager specifically about the overtime. Try to understand why he expects you to stay later. It may be difficult, but try not to be defensive (we're Canadian, so friendly is our nature). You should explain to him your thoughts on overtime. Ask what he would expect you to be doing with the extra time in the office, and why the work would not have been scheduled to be in regular hours.
As far as LinkedIn, talk to him about that too. Why is it important to them that they be on your LinkedIn page?
Most important, make the project manager understand that you really do like the product and the work. If the work is getting done, and you like the product, that is probably the most important starting point.
Best of luck.