My husband and I tried for about a year to have our first child, and what finally ended up working for me was using the ovulation testing sticks. You just use them like home pregnancy tests, and it really helped me pinpoint the exact day of ovulation.
No position is any better than another, the whole gravity thing isn't true because sperm actually swim upwards thus defeating the purpose behind raising your legs up after sex.
You've probably already heard this, but eliminate stress from your life as best you can. Also make sure your husband is doing everything he can to help. My husband's low sperm count is why it was difficult for us to conceive the first time. He started wearing boxers instead of briefs, no hot tubs or saunas, no drinking no smoking and better diet really helped. Only thing is it takes 4 weeks for it to make a difference.
I don't know how often you have sex, but it might help to cut back on it if you're doing it every day. Once every three days is optimal for having the best sperm count in the ejaculate to increase the chances of a sperm getting through. I knew about when I would ovulate, so we wouldn't have sex for at least 4 days before I would start ovulating so he would have more sperm available for that two-three day period.
The second time I got pregnant the first month we tried, so I think his better health and keeping his balls cool helped us a lot.
Best of luck to you, and no matter what try not to worry about it (I know, that's the hard part). Just relax and have fun