I think you're very young to be sleeping in separate rooms. However, if you've BOTH talked it over and agree with it, then do what feels best for the both of you. No one knows the state of your marriage like the two of you.
My parents have had separate rooms since I was 16. Mama reads until the wee hours and my Dad had to get up early for work. They've had to replace the carpet down the hall between the rooms MANY times
They're in their
70's now and still hold hands when they're out. They kiss hello in the morning and before either leaves the house for ANY reason
I guess what I'm trying to say is that separate bedrooms doesn't have to mean separate lives or trouble in the marriage, but I, personally, would get a bigger bed no matter what.