As you have found PCOS can make weight loss more difficult but we do know that lifestyle changes are really important for managing the condition and even small amounts of weight loss (around 5-10% of weight, which would be 3.5-7kgs for you) can really improve the symptoms of PCOS (including acne and menstrual irregularities) and fertility, as well as reducing the longer term health risks such as diabetes. Assuming no other problems with fertility, with intensive lifestyle management and possibly the addition of medication there is no reason to think you won't be able to fall pregnant. However if your periods are irregular it may obviously take longer to fall pregnant.
It sounds like you have already made some lifestyle changes but it may be that you need some more specific dietary and exercise advice if you are not seeing any improvements in your weight or symptoms. It is difficult to give any advice without knowing your history and what you are currently doing but you could consider seeking help from an Accredited Practising Dietitian and Accredited Exercise Physiologist who have experience with women with PCOS who could provide some more individualised advice to help you. You might also want to see an endocrinologist or gynecologist with experience in managing PCOS, particularly if you are wanting to concieve soon.