you only really need one tank for this fight but the DF will always go with the standard template of 2 tanks, you are lacking DPS and your main tank will always be competing hate with the 2nd tank, which is pretty inefficient.

The only advice i can give is, make a party on your server via shouts, make sure everyone knows the fight and are decently equiped. Or join a FC/LS get people to help you.

This fight is very bad against healers imo, they have to avoid puddles/landslides, keep everyone alive during stomps, babysit the main tank so he doesn't get one shot by mountain buster and maintain hate so titan won't cleave everyone down. I have the utmost respect for healers than can beat the fight legit.