Question on switching out LOR writer?

[cbx2v]

I'm applying to masters programs in public policy (IR focused) and I'm wondering whether I made a mistake on one of my LOR picks. I chose my current supervisor (been there for three years and he said he would write me a stellar rec letter) and two of my professors from undergrad who had written me letters in the past. 

Now, thinking about it, I'm wondering if I should have asked a supervisor from my year long internship after college rather than having two professors, since these programs are professionally focused? I just picked the two professors because they had written me supportive letters previously. This internship was abroad and now that I'm working on my statements, resume, quant resume, etc. I realized that a lot of my best stories/ experience comes from my time at this internship. Will it look weird that I didn't get a letter from them?

I have just enough time to switch out letter writers, though it obviously wouldn't be optimal...

Thanks!

[DBear]

Personally, I'd say swap out 1 for the internship. I also attended a program geared towards producing policy professionals and I had 1 professor, 1 from an internship and 1 from my then supervisor. If you can get the person from your internship to speak to how that experience ties in with what you want to study and how you were able to demonstrate effective application of stuff you'd learned during undergrad, I think it'd be a stronger letter. Also, if you have 3 letters from people who know you in different contexts, that may paint a more comprehensive picture of who you are. 

Just my 2 cents