i would recommed you doing normal dips until you gained enough basic strenght. than you can go to for example "leaning forwarddips", they build more chest strength however i would recommed you stick to normal dips and work regularly.
Dips are the exercise where i can see my best progress, i can remember the first time trying dips (i even could not hold the support hold for 10 secons) like it were yesterday.
and daniel is right, don't stress yourself.
keep up the good work!