Hmmmm - a few ideas to think about....
If you are still giving the BF at night, have you eliminated all dairy from your diet? If not, then I would suggest that to start with, as he will still get the milk YOU consume through your breastmilk. It may be that he is still having some tummy pains from that trace of dairy and it is putting him off of eating.
I personally disagree with your HV about getting him onto the 3 full meals at this age. Especially if he is not enjoying his solids, then it would only cause him that upset and stress more often in the day. My thought is to cut out the dinner time meal, and stick to just twice a day, for starters. You may find (hopefully) that he takes more milk as a result. I'd also keep giving him pear puree for his breakfast, if that is what he likes to eat, then he may come to enjoy it even more, and be more relaxed at mealtime. Actually, looking again at your list of what he likes to eat, I think it's a pretty good and varied list for a baby not even 7 months old yet! Offer him in a relaxed way, his morning purees, something he does like, and do it in a chilled out way. Does he sit in a highchair or a bouncy chair or something? If so, is it possible he's not comfortable or doesn't like where he is sitting? Even though my DS is more than happy in his highchair 90% of the time, there are days he refuses to eat because he just isn't happy sitting there. I pick him up and either sit him on my lap or hold him on my hip and feed him that way. A bit less comfortable for me, though!
You can also mix milk in with his sweet potato or other creamy purees, to get him an extra half ounce here and there.
I also would take him off of the weetabix. Wheat can be allergenic (perhaps that is causing him some tummy discomfort and food aversion?) and it's also very bloating, so at this age, maybe just try the fruits, not adding a grain. Even cut the toast out for a while.
Although there is sort of a "window" of opportunity to get LOs to eat a variety of foods so they aren't as fussy, I wouldn't stress about it at 7 months old. Your LO is only just starting to "get" the idea of eating, and you've got loads of time. Just try to stay relaxed about it or he will pick up on the stress of the situation.
I would also listen to your HV with a wary ear.....there doesn't ever seem to be any consistency in what they tell people, they all just go on their own personal guidelines and half of them (in my experience) don't know what they are talking about. Smile and nod and say "oh yes I feed him loads...." The HV at my clinic told me she had never ever ever heard of waiting until 6 months to offer solid food, that my son was suffering because of it, and that whoever had told me that was horribly wrong and didn't know what they were talking about!
Milk is most important and your LO still needs a pint a day -- about 21 - 24 ounces -- and so I would concentrate on getting his milk up and not letting him fill up on solids. Adding milk wherever you can to his food can help increase that.
Not sure if any of those ideas give you something to think about?