Being skinny and short does not restrict one from working in the plants. When I started almost 33 years ago I was also skinny and may be weak physically(which I am still) but that did not hamper my chances. If one is fit one can undertake any job. Research and teaching also demands physical fitness. In chemical plants one doesnt have to lift weights which really needs manual strength. The job in plants is mostly to monitor processes, and with latest instrumentation this is almost like working in an office.
Also I would suggest to join a organic chemical industry rather than inorganic, something like specialty chemicals. To get hired the first thing required is clear chem engg concepts, the basics. There is a myth about chem engg that it is based on chemistry. I would say the basis is physical chemistry, but it is highly mathematical.
Secondly to develop passion one needs to go a little deep in any subject. For diploma the real chem engg subjects like mass transfer, transport phenomenon, reaction engg are not taught in depth. Unless one learns these subjects in depth one cannot get the real feel. My advice is try to get into degree . It is easier in India if you can afford to come and stay .
Environmental engg has very little of hard core chem engg and it really doesn't need a specialist like chemical engineer. Chemical engineering has many facets like R@D, PILOT PLANT SCALE UP, PROCESS DESIGN, PROCESS ENGINEERING DESIGN etc and one should choose depending on the aptitude. Applied chemistry is not chem engg. Try to get into a degree course.