HELP - my 38 month old daughter is not potty trained as yet

I have a 38 month old daughter who refuses to go on the potty without her diaper and pants on.  She will gladly sit on the potty with clothes on.  She will empty her soiled diaper into her potty, take the potty connection off and dump the BM into to the toilet, replace the potty connection to the potty chair, and flush the toilet.  She will not, however, pee or poo in the potty chair.  She tells my husband and I it's easier for us to change her in her diaper.  I tried potty training her once and she stayed in her wet underwear for 20 minutes constantly asking me to change her.  I felt so bad, that I changed her into her diaper after that.  What can I do to get her to be potty trained?