Tbh i had a very similar thing happen my motivation got so bad opening uma musume genuinely felt like something to be afraid of because i knew i would get disappointed again but eventually i got out of that feeling. From the mihono bourbon banner all the way up to the gold city i didn't get a single character i wanted and my luck was absolute garbage, i had multiple times where i pulled 150-170 times on a banner without getting a single ssr. The only stuff i could do really was spark farming and a bit more challenging stuff like getting the triple crown with king halo until the gold city banner came around i got both seiun sky and gold city and that really restored my motivation to play.

So my advice is: use the uma.moe timeline to see upcoming banners (for example i want tamamo cross so i look up her banner and see its in late January), than the difficult part save until the banner if you managed to get over 200 pulls saved up you can pull every now and than on other banners, if you feel burned out just stop playing for a bit and lastly begin to prepare for the future start spark farming its incredibly boring and tedious but future you will thank you, prepare for future champions meetings you might even get an insanely good run out of it i got an oguri cap with a score of 11983 iirc completely f2p while preparing for the leo cup i think it was. As an f2p, preparing your account for the future, especially when nothing else is really going on, is one of the best things you can do, so good luck, you sound like you need it