How do I get my 10 month old to stop sucking her thumb???

My daughter threw out her pacifier at 2 months old, at first i was happy- i thought Great! i wont have to deal with trying to take it away from her, but at 4 months she started sucking her thumb. I thought it was cute and no big deal- pluse its convienent for me because thats how she self sooths. But now she almost a year old and im realizing this is going to get worse as she gets older. her doctor suggested that i get her to use the pacifier again, which will be easier to cut out later on. when i tried that she literally threw it out when i give it to her..... thats my story, what should i do???