No you shouldn’t be ashamed. Try having a BA in Japanese, then going to Japan for the first time and only having Korean words in your head while you’re there. Getting lost on the trains for 8hrs trying to get from Osaka to Nagoya to see your friend because you’re so incompetent in the one thing you dedicated the majority of your life on.
I have this problem because I completely burnt out on Japanese in Uni. It can happen if you overload yourself. At the end I just couldn’t function anymore and started focusing solely on Korean. My love of Japanese has returned after a few years hiatus and now I’m trying to piece together my knowledge. I often feel ashamed because I feel like I lost all I worked for for those nine years(I started taking classes in 7th grade), but when I use this site and Duolingo I see I know more than I think I do. It was good for me to have that break because I lost why I enjoyed Japanese and was able to regain that love that I originally had.
Language is tough, but I think you may be similar to me in that you know more than you think you know. It’ll take a while and lots of repetition to pay off.
I don’t know how long I can keep going on this site, so I’m only doing the month by month payment. Because I may have to stop at any time if things get busy. I might move from S.Korea to Sri Lanka in as soon as April to as late as a year and a half from now. I have no idea what life there will be like for me and how much time I’ll have. Now I’m learning Korean and Japanese at the same time. While I’m there I’ll continue Japanese, Korean, and will start learning Sinhalese.
Long story short, don’t feel bad. Don’t feel ashamed. Language is tough. I’ve been studying Japanese a long time, it’s my degree but I consider myself incompetent BUT I know more than I give myself credit for. Don’t burn yourself out. Study at your own pace, find ways to study that are interesting to you. You like WaniKani and are learning from it? Keep at it. Don’t know if you can use it as fast as you’d like to, pay month to month, and try to make the most out of it each month. If you feel yourself using it less often, take a break and try something else for a little bit (even if it’s just carrying small flashcards where ever you go).
Side note: Another thing that can help is to find a movie that you like a lot. Watch it with Japanese subtitles, and see how much you know. Keep watching over and over again. Remove the subtitles, keep watching over and over again. Pause and try to translate parts you don’t know. It’s a slightly different method to learning natural Japanese than traditional studying. You can learn many things without worrying about rules, only focusing on comprehension.