I strongly recommend against annexing one province minors. It results in 6 Bad boy (the stat displayed under stability) and if that gets too high then your nation is likely to have a civil war. Over 20 bad boy and you're already almost doubling your stability cost. Go over 40ish and it's x4. What difficulty are you on?
Also, tech sliders I'd recommend going full Infrastructure until level 3 or going full land. Most nations take 45 years to get to land level 2-3. If you really concentrate on your economy then you should be able to catch up on the military technologies quite easily. There's not much point balancing your sliders evenly... concentrate on one thing at a time.