Yes sweetie, congradulations on how long you have nursed !
I think that the biggest problem we extended nursing mothers face is that we do not have enough examples in our culture that represent the beauty and normality of toddler nursing. We whole heartedly desire to break through the barriers and challenges of nursing, but after a while we feel the pressure inside and out when reaching 12 months or more. We press forward knowing the benefits, but not knowing through example some of the normal, yet annoying, issues we will have to come to terms with.
I too felt bad about nursing my toddler; not so much due to my son, but more so due to the stress of dealing with a troubled marriage, having horrible pregnancies, being criticized, and not copping well myself with things. We encounter situations that may not seem to affect us at first, but when we feel annoyed beyond expectation regarding normal occurences, we show that something is not quiet right internally. This affects our tolerance level when normally we would be able to better tolerate them.
So I say if you are not able to get pass the negative but normal feelings, then try cutting nursings down to those times when you both enjoy it most, like before bed or naptime. If after that you feel horribly annoyed then you may want to completely wean, instead of having unpleasant memories and feelings left.