There are different ways you can approach Baby Led Weaning (in my opinion even if it does not say so in the BLW book which I have not read). In my view it is "baby led" with one of the main aspects being that there is no cajoling into eating, no "come on eat up!" or "here comes the aeroplane", no "one more bite" or trying to prise their mouth open with a spoon to get some food in whilst they are distracted by the ipad or a toy, these are parent-led more than baby-led. So, it's about baby leading the way, being interested in the food and wanting to get it in her mouth,if she is not interested it doesn't matter, when she is not hungry she doesn't eat, when she is hungry she makes it clear and eats to her fill and then stops. The parent-led aspect is that you offer safe and healthy balanced foods (by baby-led it doesn't mean if she wants a giant slab of chocolate it's ok, they don't get to lead that much!).
Once you think of baby-led in this way it takes the pressure off of how much she eats, or if she is able to pick up the food and bring it to her own mouth. If a LO is indicating a desire to eat the food you serve but cannot pick it up I see no harm at all in picking the food up and holding it out to offer it to her, so she can grab it and bring it to her mouth (picking up from the tray is more difficult and takes a certain degree of fine motor and coordination which she may just not have at 7 months), I also see no harm in holding the food for her and allowing her to bring her mouth forwards to the food to eat. Both of these have body language and indication she wants to eat and are baby-led IMO.
My own DS was desperate to eat and the frustration if he could not pick up the food or get it to his mouth fast enough was very clearly indicated through body language and verbal sounds so I helped him. A few times this meant holding the food for him to gnaw on, he might hold my hand and control the eating that way by pulling my hand to his face or pushing away, also moving his head towards or away from the food. Some times I just held up the food so he could get a good grip on it. It also depends on the foods offered, something very slippery may need more help, something drier may be easier to pick up and hold. I did encourage him to hold the food and self feed, for instance if he did the little bird mouth open thing at me and not even move his arms I might say "here, you can take it, you try" and when his hand came up I'd help him grab the piece, but I would not have gone to the extreme by saying "if you can't pick this up yourself then you don't get it", yk?
Larger wedges and foods that are drier on the outside will be easier to pick up. Small pieces of food take much greater skill and the development of the pincer grip (which I believe is one of the benefits of BLW down the line, these skills are practised more than a spoon fed baby). A large potato wedge or sweet potato wedge baked in the oven for instance will have a dry outside, easier to pick up and grip, whilst the inside will be very soft and easy to suck and gum on. A curve cut (crescent moon shape) is easier to hold than a straight cut, or a notch cut into a food or a bit of a squish of the food may also provide more grip, pasta twist have more grip than penne for instance. Slippery foods such as melon might be serve with the skin on to give grip, you can tell LO that it's just the soft part they eat, not the skin, point to it, explain, and their mouth will also tell them which part to eat, or if the skin is not on then giving the food a little notch or squish in one place gives more of a grip.
It's perfectly normal for a 7 month old not to be all that interested in eating lots (just as it is quite normal for another 7 month old to be very interested) so try not to worry. I've seen LOs at 7 months who barely take a bite and by 9 or 10 months have a huge appetite for solids. It's all ok. Part of this process is also about learning the social aspect and family aspect of eating, sitting at the dining table to join in with meal times, seeing you eat and use cutlery and cups, seeing the norms of meals times, becoming accustomed to the foods you regularly serve within your own family by seeing and smelling them, touching them even if she doesn't eat much of them initially and even if some foods are prepared slightly differently for her to accommodate for her age and development.
I hope this helps some
