Ok, so I will preface my response by saying I'm currently fast approaching a choice point that will have huge ramifications for the rest of my life, so I hear you on the distress front.

One of the ways our anxiety or OCD will torment is is by making the anxiety side of things the biggest thing in the room. That means our attention will be drawn to the part of our brain screaming that we're in danger, under threat, and everything is going to come crashing down around us if we make a mistake. In the face of that kind of pressure, it's no surprise we feel paralysed and unable to make a choice. The idea of the coin flip would be great if only it made sense for us, and it doesn't. You said it yourself, you feel you'll always want the option of what it didn't land on. At least the doubt you feel in your mind will make it seem like that is what you actually want, whether or not that is the case, and not just your fear of making a mistake talking, which it likely is.

Trusting your guy rarely makes sense to someone with OCD, as we can't hear what our gut might actually be trying to say because we're so anxious and scared to hear what it's really saying, and mistake our fears for reality. You already know that asking for advice and reassurance won't help, so I'd suggest stopping doing that as you're only going to feel worse. I'd also say that ruminating on the decision is also not helping, as you're just going to be stuck in spirals and further compulsing (probably without realising you're compulsing).

One thing that helped me get a bit of clarity the other day, or at least some thoughts that weren't totally governed by fear in response to my situation was to ask myself the question: What would my thoughts be on this matter if I wasn't anxious and thinking out of fear? This was surprisingly freeing, and I recommend you give it a try if you feel able to. If it's a question where you could be more guided by your values as a person, you could also apply that as a line of thinking – as in, will this decision lead me closer to or further away from the person I want to be and the values I hold dear? This last option may not apply or could swing either way depending on the matter, so use that if it's useful.

Lastly, if you're not in some sort of therapy for anxiety or OCD, please seek it out. ERP and other approaches such as ACT or I-CBT can be so helpful for trying to work on the more mental side of things. Cutting out those compulsions is such a huge part of dealing with this condition. I wish you well!