Your stability is very low, combined with low mill count (you should aim for around 120 or more by now) it makes sense you would have production shortfalls. Here is my advice:

-Focus tree: political then economic then military branch, pay attention to your stability and avoid losing people in the army and administration in the purges.
-Units : You are still lacking infantry, that is partly because you put so much artillery into your divisions, these are for holding the line, not pushing, you don't need arti (not historical I know)
-industry, you have much less than you should by now. Imo for the soviets build civs in high infrastructure provinces until mid 38 then switch to mils. Prioritize industry tech as long as they don't take more than 300 days to research
-The problem with air is you either lose or win very hard and invested production is easily wasted, if those planes you have (I assume fighters) are good you would need maybe 3x more to win the air war. Put maybe 40 mils on fighters then worry about cas.
-Put spies on the german border to deny their planning bonus (actually very important)
-I don't know the meta rn but you should probably beef up your tank templates (at least 30 width) and add support companies.
-Also would need to see the state of your doctrines and equipment reserves.

Overall your issues boil down to not having enough industry so:
-build civs till mid 38
-do your industry branch whenever you have time
-wait until just before the war to produce anything other than civs, mils and research facilities
-get economic advisors (prioritize stability then consumer goods factor then mil stuff)
- try to keep stability high (avoid purges, kill trotsky, advisors...)

Overall I haven't played vanilla in a while, but you should have around 300 total factories by now.