Been bootstrapping a HaaS company for 3+ years after quitting my job. Some good SaaS-specific advice has been given above but the fact you've been struggling to develop a finished product in 3 years, which is almost an eternity in software, sounds alarming. I'd look into this oddity and assess your execution capability if you switch to full time. It does liberate you and definitely advances your business faster but doesn't make you a super hero either.

Also, consider the typical financial advice: don't quit before you have a 6-12 months cushion to face tough times. SaaS is hard.