Good for you finding out that you enjoyed temping - you absolutely would be helping people within admin, this is a very necessary sector, I am concerned that you won't allow yourself a job where you feel happy - do you not feel you deserve happiness?

Social care and the fulfilment from it is often overrated IMO - how you feel within that sector is not unique, and it certainly does not mean you are not a good person or a caring person - actually it may be that you care too much, that the suffering you see overwhelms you and impacts on your well-being.