I assume TS was referring to "upgrading my squad" as putting fancy fancy gacha only girls in his squads since he is already at 12-3. If that is the case, then he is out of luck unless he spends real cash. For me flower gems are just a luxury not a necessity. As Victor already said, You can clear the stages with a competent 3* team.

And also ive been playing this game since the beginning and ive only done my 1st 10+1 roll almost a week ago (I have itchy fingers so im having a hard time saving up to 50 gems and spent some on increasing character capacity since you'll need alot of space for stock piling manyus and bloom dragons for future upgrade/evolution) I already have enough 5* units which mostly consists of event girls to fill up 3 squads so 2 weeks in this game isn't enough play time to consider quitting unless you are impatient.