Questions about my Spanish citizenship

I am currently living and working in London right now but I am a spanish citizen. I am a naturalized spanish citizen but I was not able to do my oath taking. And I only resided in Spain for a year and few months. And my DNI is also expired for 5 years now. I am just wondering if there is a high chance that my spanish citizenship may be revoked because of that. I also need to renew my spanish passport soon and I don't know if there will be problems then.

You raise an interesting potential

Except in exceptional case spain requires one to renounce any existing nationality when they assume Spanish nationality.

  If you are suggesting they could in effect strip you of your Spanish nationality that would leave you stateless

I cannot image that would be a possibility   

Why don't you contact your (spanish) Consulste in U.K. and ask ?