You definitely need more speed, looking at your lens line up. I have a K-7 and my shutter count is past 40,000. Based upon my experience, you definitely need some faster lenses: typically f1.4 to f1.8. You will need to consider fast primes, because the prime lenses are the only options for wide aperture. In my case I have a mix of fast MF and AF prime lenses, incl. FA Ltds (f1.8), a f1.7 and two f1.4 lenses.
Since a lens is an investment, I would suggest to invest in some fast lenses first. The K-7 works nicely with fast lenses. Anecdocticaly, I remember, a couple of year ago, shooting at sunset along the coast in winter. I had to put on my fast lens at about 19:10; other photographers with Canikons stopped to shoot at 19:20 because ti was too dark. With my fast lens (VL58mm f1.4 in that instance), I was still shooting at 19:45 with my K-7, and a Nikon user (a big FF Nikon with a f2.8 lens) told me that he was shocked to see me still shooting.
Practically, if your budget is limited you may consider some older manual (MF) lenses. Pentax has a lot to offer in terms of older vintage lenses.
Would a newer/faster camera be a better option? NO definitely IMHO. I have both K-01 and K-7. The K-01 is superb at high-ISO compared to the K-7. But the high-ISO capabilities do not replace some fast lens(es) with excellent IQ in low light conditions.
The K-7 is still a great camera at low ISO, and I continue to love using it. I am obviously not the only one:
https://www.pentaxforums.com/forums/pentax-dslr-discussion/224071-summer-adventures-k-7-a.html
In low lights, some fast lens is the best option and it will give you some options and capabilities beyond your 'wildest' expectations.
Hope that the comment may help.
Last edited by hcc; 05-11-2013 at 04:48 PM.