Withdraw is not birth control.
It's kind of odd you mention his dietary supplements if you're not letting him ejaculate in you.
Here's what I'd do: Step 1)start using birth control immediately. Step 2) Address any lubrication issues you may not be aware of. Insist on using copious amounts of lube for the next few weeks and see if that helps. This may sound stupid but you may not be as physically aroused as you need to be. Stress or emotional problems in the relationship can add to this. Insist on lots of foreplay and in taking the action a little slower for now.
Do keep your doctor informed. If you don't feel like you're getting anywhere with this doc, visit another doc for a 2nd opinion. Some STDs or other diseases may cause discomfort during or shortly after sex. It's odd she isn't culturing to see exactly what is going on. Maybe the antibiotic/antifungals she has given you were just not the right ones.
Do be aware that intermittent periods may be a sign of hormone problems and/or PCOS. This can also affect vaginal lubrication. Going on The Pill is one way to help your body keep on cycle. Some doctors may do blood work to assess hormone function. Talk to your Gyn doctor.