The large fat parts are about the size you should be going for and I also agree that they are growing tall and thin because they are trying to reach up for some bright light.
Bright light does not always mean direct sun but good light can be obtained by setting the plants close to a sunny window but NOT against the glass or set on the sill unless you have a little shade at the hottest sunniest part of the day. All plants go leggy like your when they are deprived of proper light.
Hope all this helps you out a bit and the plants can improve. you can also remove the tall bit's IF you like or even cut them down a bit, don't touch the cut wounds as they need a few days to a week to dry off as these plants hold a lot of water within the tissue of the green shoots.
Good luck, hope this helps a bit
Best Regards. WeeNel.
ILuveCannas, Cacti are plants that hold within their above soil greenery, lots of moisture, some it is like water, some it leeches out like a thick clear jelly type substances, so you need to allow the cut area where the moisture is seeping from time to form a crust, stops seeping, then make the hole in the soil with maybe a pencil as IF you just push it into the soil without making the hole, by pushing the crust will betorn away and the jelly or moisture will just cause the cutting to rot away in the soil causing the cutting material to die off instead of making nice new roots.
The reason you should not use rooting hormone or powders is because these can cause the plant tissue to over react and open the cut area that you allowed to dry ready for root formation.
I hope I've explained this well enough and you can understand it all.
IF not just get back to me or someone else for clarification.
Good luck and best regards. WeeNel.
Unless you live in the desert southwest where prickly pears root like weeds regardless of what you do to them. I've had good results by just sticking the pads directly in our nutrient poor soil in 100+ F weather without previous drying (I also don't water them much beyond the first week). I suspect I probably don't even really need to put them in the ground as fallen pads frequently root themselves in my garden without any outside help. They're a bit of a nuisance around here. It's not uncommon to see stray native prickly pears growing on palm trees and roof tops around here (although I imagine those were not started from pads).
I think hinoeuma makes a great point as regards the plants that drop onto the proper growing medium, they don't require all the extra attention we, as gardeners think they need however, as most of us are trying to offer a growing soil/ light / or temp the plants require, then sometimes we have to try replicate what will encourage the plants to grow for US in our artificial environment and most times it works out, but on other occasions, we just have to try even harder just to enjoy what others call either weeds or prolific spreading plant, yet for some of us, they just sit doing nothing except die on us. Without help that we can offer the plant to grow well for us outwith their natural environment, guess as gardeners we all like a challenge LOL.
There are some plants that does not make good houseplants. Prickly pear is one of them, unless you have a geenhouse. They need full sun and winter shill to go dormant during winter, as nature intended. They grow wild here on the prairie, Wyoming