Don't worry about good and bad too much in the initial stages of improvising, plenty of time for self-assessment in the decades ahead of you. The first thing is just to get some sort of reliable flow going and enjoy yourself, and as you obviously have an intuitive feeling for phrase and rhythm, inhibition will not be the problem it is with many players. You can acquire a huge keyboard vocabulary and technique at your own pace, that isn't as necessary as most people think anyway, and it certainly isn't sufficient. Other people, even famous ones, cannot tell you what sounds you like, only you can decide that for yourself. That is a seemingly obvious fact which startlingly few people realise. We are never more ourselves than during deep improvisation.
Please keep posting your improvisations here, I look forward to hearing your music develop.