If you are eating fruit that's a speed food, then that will give you the filling power you need so you wouldn't be over consuming it anyway.
I would personally just syn your nuts and have your healthy extra B as normal. They can be high in syns but remember they're healthy and good fats, so I think it is worth spending majority of your syns on nuts as you enjoy them and it gives you more satisfaction than a chocolate bar and/or crisps would!
As for the eating out a lot and family meals, unfortunately you are just going to have to find a way around it if you are determined! If you are eating out, try opting for a baked jacket potato instead of chips, have steak but cut the fat off and count approximately 6 syns for minimal oil used! Chicken skewers are a good option too, again counting 6 syns for minimal oil.
Another option is you can just use your syns weekly instead! So if you go over one day, you will still have syns leftover before the week has finished. Some people do find they're more in control when they use their weekly syns.
I, personally, would not calorie count. I have tried it but felt extremely restricted, I became far too obsessed and even when I was at my recommended daily allowance, I was still hungry! You have to count calories for fruit and vegetables and lean cooked meats whereas with Slimming World, you don't.
Finally, you could try Keto, 5:2 or WeightWatchers. The bottom line is, if you desperately want to lose weight, you are going to have to sacrifice some meals when you go out or go to family members for dinner. It is hard, but how badly do you really want this? My husband and I used to go out 4 times a week, now we only go out once a fortnight and that's the time when I decide to treat myself.
Good luck with whatever you decide but remember: no amount of fattening or unhealthy food will make you feel good as being slim and healthy ever will!