Why doesn't my plant have branches?

It has axillary buds that will eventually grow out as branches. Based on the stature, you either have a runt / unusually small plant or possibly giving too much light and stunted its growth, which would probably delay branch growth, too. Unfortunately it looks a bit runty (genetics). Reduce light 10-20% and see what happens over 10-14 days after that. If stunted it could take a while to snap out of the funky growth pattern. It will not correct itself overnight. There is hope.. looking at previous weeks the droopieness indicates too much light at times.. or ramifications of bad watering habits due to context of tiny plant / large pot. If it's a runt, probably just get weak or slower growth due to less light... but if it is a genetic runt, it'll never grow properly regardless of what you do. There's no fixing a runt. Some plants just take longer for the side branching to start, too.. they are all not the same in this regard, but they all do eventually branch out. If you see the "axillary buds" at each node, it has branches... just not formed, yet. Give it another ~2 weeks and see if growth normalizes... heck, if you want to practice on it, keep growing it, but it's going to be a very small yield. Probably won't justify the cost of electricity. Unfortunately, it's an autoflower, so it'll probably go into flower soon, if not already, and you'll end up with a 10-15 gram harvest for ~3.5 months of work. If you already can see preflowers at nodes (don't confuse with axillary buds), it's already sexually mature and in flower phase. Grow photoperiods at least until you learn how to confidently grow the plant. Autoflowers are not forgiving of mistakes. Even after that.. stick to photoperiods, lol.. they are better plants. Anything you can do with an auto, you can do with a photoperiod, but the opposite is not true. If you want a 'fast' plant you put it into 12/12 sooner... and it's the same timeline as an autoflower.. the only benefit an autoflower truly has is growing outside and out of season when the length of day and night won't allow flower phase. -------- I don't care what 'they' say.. even an autoflower should be in a size-appropriate pot and increase pot size as the rate of drinking warrants it. If gently potting up a potted plant ever stunts a plant, that person should quit gardening completely, because they are terrible at it. I say that with the confidence that even forrest gump could pot up a plant without issue. I've done it around 400 times in 7 years and yet to see a plant get stunted. The risk is miniscule to nonexistent - it's an urban myth. Proper root growth and sufficient moisture will prevent any rootball from deteriorating while you do it. Loosen it from the sides... press a bit on the bottom... after that it slips out easily. In fabric pots, you may need a trowel or something to separate it from the fabric along the sides, if slightly overgrown - no big deal. You can fold down the fabric pot until it slips off, if you want.. you can get the fabric pots that utilize some velcro and that makes it even easier. The idea that "transplanting" is stressful comes from outdoor gardening context. When you cut through roots to transplant a plant in the ground, you do significant damage cutting off the vast majority of its roots... this does not happen in a potted plant. All you do is gently pull it out. Gently place it in a half-filled pot and gently cover it with medium to level it out.. gently. LOL. No tearing, ripping, destroying the rootball in any way and bob's your uncle. But, even with an autoflower, you'll get more consistent results using a size-appropriate pot. It'll make irrigation simple as 1-2-3, too. 1) fully saturate, 2) wait for appropriate dryback and repeat. These are standard practices for potted plants and marijuana isn't a unique case. If soilless, also get 10% runoff or more, religiously. Easy as pie. Watering a tiny plant in a large pot is difficult and should be avoided. It'll cause infintely more problems than potting up as needed, which again causes zero problems with minimal competency.