eBay does not "remove negs "from any seller who contests them". Anything but. The reality, as we know from sellers who complain that feedback was unfair, is that it's very hard for them to get negs removed. eBay's policy is that the buyer is entitled to express their opinion of the buying experience.
There are however rules about what can and can't be said and when either buyers or sellers break them the feedback is liable to be removed.
Although you only have 45 feedbacks yourself, it sounds as though you may have left an unusually large number of negatives if so many have qualified to be removed.
However it's impossible to offer any advice as you haven't told us what you said that was removed, and have made all your feedback private so that no-one can see what previous feedbacks you have left.