A Too many teachers wait too long before applying for promotion. You have already gained a lot of experience. Although you have much still to learn - indeed, we never stop learning - there is no reason why you should not test the waters. Schools are going to need many more senior staff over the next few years to replace those who will retire, and someone who has your keenness is to be encouraged.
I do wonder about a small school, though. There will be a heavy teaching load and less time to specialise. As an alternative, you could consider an assistant headship in a larger primary school: the money might be about the same as a deputy headship in a small school, and you could continue with some of your areas of expertise in more depth. Although not common, such posts can be found more frequently than a few years ago.