I do something similar when writing email or texting etc. I write as much of what i want to write using my existing vocabulary. I change what i want to write as much as possible do it fits with my existing vocabulary.
However i recognise it is limited. Sometimes I need new words. Of course I do. But once a word is added I try and reuse it as much as possible.
So yes I now know llysiau, pys, halen, pipir, garlleg, sos, sospan, berwi, ffrio, cig moch, wy, melyn, melynwy, menyn, selsig, tatws, cartref, canol, beic, popty, meicrodon, pysgod, sewin, gwyliau, yr almaen, ffrainc, ffraneg, gwlad belg, almaeneg, awyr, awyren, gwesty, ty bwyta, bwyd, caffi, dosbarth, mathemateg, etc etc etc.
I have learnt my colours. Learnt the weather. Basic directions. All things i have learnt through things i want to understand from programmes I watch or from messaging people about the things I like to do. No surprises, i like cooking, eating out, holidays and i work as a teacher.
I am not showing off. Anyone who has spoken to me in Welsh knows i am a very nervous welsh speaker. In a cafe at the weekend i was once again shaking with nerves at asking for a black coffee and saying no thank you when asked if i wanted something else.
My point is that SSIW cannot provide you with a wide enough vocab on its own. However it works so well it gives you a great foundation to be able to pick things up but in order to progress further you need to find a way of extending your learning. S4C player is for me great. I can choose a program of my liking. Watch it. Find new words. Watch another porgram and then understand more. I can then talk to people about these things and improve my confidence. Similarly as i live in wales i try to read road signs in welsh, look at shop signs in welsh. The more i use things the easier everything becomes.
Sorry for another very long post. I’m just offering people somesome ideas of what has worked for me and hope it helps.
I sure regular forum readers know I am someone who has lived in Wales all their life but outside of a couple of years very poor secondary welsh education 35 years ago have never learnt any Welsh. But despite my lack of confidence speaking I know of several people who react with total disbelief that I only started with SSIW 14 weeks ago.
This is down to the brilliant course. However we have to extend it and I hope my experiences can help people too.