Are my buds small?

Hello,
I started my first grow on the 7th of February, all has gone well and has been a bit of a journey at some points, but now I'm coming to the last couple of weeks I noticed that the buds are kinda small compared to other autos I have seen. The trichomes are cloudy so I think I'm going to start flushing within about 5 days.
Do these look small or is it just me?



What I'm using:

Viparspectra 450W LED
5Gal fabric pots
70% canna 30% perlite
GH flora trio + calmag + pk 9-18
3x Critical auto from Royal Queen Seeds

I water them once a day if I can but due to water issues, it's usually every other day around 1-2 liters each.
As of today, I am feeding them - 4ml micro, 8ml bloom, 1-2ml pk 9-18 per gallon
Watering has been an issue during the whole time as ppm of tap water is 600+ and distilled comes at a cost but I have not been able to water till runoff as that requires 3 liters minimum to get any runoff what so ever.
A couple of weeks back I had to flush them as I believe they got nutrient lockout but as of now they seem healthy again and am not going to start reducing nutrients over the next week.

The picture below is from 7 days ago.




My questions:

Is it better to do a photoperiod?
RO system?
Are my plants small?
canna a+b or GH flora trio?
Cant afford better LED but maybe swap the viparspectra with a 250w HPS?
Would 3 gallon pots be better?
Are they ready to flush?


Feel free to give any tips for next grow or some opinions about my first grow would like to know what people think.

Thanks in advance.

I can't answer all the questions but I'll do my best the buds do look quite small for the amount of power that you're getting with those plants however in my opinion you shouldn't water them as much as you are. And you should definitely defoliate the bottoms of the plants to get those leaves out the fan leaves to be exact you can also take the fan leaves off on the lower parts of the plants to uncover lower parts of the but so they can get light as well. When I do flower stage in the first month I will feed nutrients but the buds will swell up in the last few weeks of flower. Flushing will also happen in the last two to three weeks of flower to properly flush your going to over water the plant wait a few minutes and then water the plant again do this for the next few water cycles up to two weeks.