I can go along with your paraphrase as examining the poem as one long sentence, but there is no denying Emily's penchant for full stops within a stream of consciousness, even if one could describe her thought process in such a way. I also don't feel that 'warrant' connotes a double usage here. I think it is stating explicitly that she expressly concurs with her inner feeling that she is once again experiencing the mixed emotion of the 'hurry with a lingering.' And 'to be fair,' that is, fair to herself and fair to her assessment and self reproach at once again feeling 'the old desire.' I don't link the use of 'fair' here with a physical description in any sense.

It is also interesting that the only line that does not contain a capitalized word aside from the initial word is 'I feel the old desire.' I don't know if the whole poem revolves around 'feel' or not, but I'm thinking she could have capitalized desire to round out the trend. Of course, this also plays into my cipher theory.