How Long Does The Sutures Take To Dissolve Post C Section?

Hi dr. yesterday i went for my 6week checkup. my son was born on 20 jan 2015 via c-section. My giney said all is well but i do however still have internal stitches. my question is if it is still normal for them not to be completely dissolved yet as she did not do internal exam, she FELT them? She said it is normal and on average it takes about 120 days? I am allowed to have sex and am cleared for normal acctivities, but i m worried that the internal stitches may cause the wounds to open up or even rot being not dissolved after its been 6 weeks now! is it normal, when will they dissolve and heal completely anf how could she feel them?