For as long as Britain is in the EU, negotiating leaving terms whilst hamstrung by a minority government, the EU is in control.
Britain should leave, without agreeing any terms, then start negotiating.
This would force the EU on to the back foot, desperate to preserve access to the UK market, whilst leaving Britain free to immediately negotiate non-EU trade deals. Had Theresa May done this two years ago, Britain would already be thriving, but she is inclined to personal animosities, and has a poor ability to foresee events. In other words, a poor leader.