Is it possible to use my watch to control Spotify music without headphones?

Yes.  There are music controls built onto the watch.

Yes, but whenever I try to use them the watch says I need to connect headphones

Oh, you can't use the watch to remote-control some other device playing music.

I thought you meant when you have a bluetooth speaker attached to your phone.

I have a waterproof UE Boom and I have it in my shower, you can't control music on the UE Boom but you can on the watch, because the watch is the device playing music. So as I'm dancing around in my shower (there's a mental image you didn't need) I use watch to change tracks/volume etc.

You can't control an iPhone or a Computer etc from your watch, no.

So I can control the music playing as long as the speaker is connected to the watch via bluetooth instead of headphones?

Not what I expected, but totally works for me

Thanks 

As long as the watch is the device "playing" the music, you can control it.

Yes you can. When I press start on the watch music control the Spotify starts on my iPhone 

I use my F6x to control the Spotify on my phone, which is connected to a UE Boom speaker. When I workout, I have my phone connected to the speaker and running Spotify. I use my watch to control the songs and volume.

Can I not use the audio speakers built into my iphone instead of headphones?

No Problem at all. You can choose

1. Control music from the device itself and Control Direct connected Media devices

2. Control the Smartphone (and whatever is connected to it)

You Just have to choose in the music menu under Providers

I am replying to muppetman’s statement above saying ‘as long as….’

^^that is not a completely accurate statement ^^. As has been stated in this thread there are TWO general ways to use your watch to ‘control’ your music. 

Scenario 1. your music is on your watch, you have headphones or earbuds or speakers ALSO connected to your watch, and there’s not a phone involved or nearby, at all. Your watch is your ONLY source for music. In that scenario, yes your watch can control your music. Play, pause, vol up down etc. yes. 

Scenario 2. Your phone is your source for your music. You have your music app ON YOUR PHONE, running your music. Your phone is with you, near you, etc. you have earbuds connected TO YOUR PHONE [meaning, not your watch). In this scenario, yes your watch can also ‘control’ your music - play pause vol up/down skip fwd, etc. In this scenario, your watch is basically acting as a remote control for your phone that’s with you - you just don’t have to use your phone (or your earbuds) to manage what’s being played. 

All this is managed by the music widget on the watch - you have to decide btw scenario 1 and 2 as I’ve stated above. One or the other - you can’t have both modes in use at the same time. But - it’s simple to switch btw the two modes. I do it all the time. Easy. 

Good luck!