As a first grow I am unsure about how my lst worke...

While in flowering the plants are growing x1.5 to x3 time the height they have before the flowering. The stretch happens during the 2 1st weeks if flowering so you can wait until there to see real changes

Pipe cleaners right.. I've seen others use those and they like them a lot. The stretch is a big part of flower. If this is your first plant take a wait and see approach. Honestly if you are new to this it's better to let it do its thing and try to keep it healthy. You'll see how it grows naturally and with your setup. Then you can do learn to do major changes after you learn to keep it healthy. I see far too many new folks make the mistake of training and abusing their plants and they make the yield suffer horribly because they don't have a healthy strong plant.

i dont know what you using there, but it should dont be elastic ! no one can tell if your lst good or bad except you , becuase you change the plant into the form you want my friend , but it does look healthy,keep doing what you are doing :D

Looks good my friend!! Maybe you can try to put your light higher to stimulate stretching, and gain a bit of distance between each internode. Anyway you're doing a good job, bravo! ☀️