You're absolutely right, that is not small - that is you turning into an experienced, natural understander of Welsh, which means that the most difficult part of conversations will be far easier for you. Da iawn!
I actually heard a thousand intakes of breath from people who still find speaking Welsh a bit stressful. Not a breakthrough? That is the ultimate masssive step from learner to speaker! Even if it's only in one situation, that means that there is a situation in which you find it natural and easy to speak Welsh. If you can da that in one situation, you can extend it into any situation where you can get exposure / experience. It'll get easier and easier.